This is to suppress irrelevant backtrace from errors raised when
delivering toots to remote servers. The errors are usually out of
control by the local server and backtraces don't provide much
information.

This is similar to https://github.com/tootsuite/mastodon/pull/5174
and shortens backtraces like below:

```
WARN: Mastodon::UnexpectedResponseError: https://example.com/inbox returned code 523
WARN: app/workers/activitypub/delivery_worker.rb:48:in `block (3 levels) in perform_request'
app/lib/request.rb:75:in `perform'
app/workers/activitypub/delivery_worker.rb:47:in `block (2 levels) in perform_request'
app/lib/request_pool.rb:53:in `use'
app/lib/request_pool.rb:108:in `block (2 levels) in with'
vendor/bundle/ruby/2.7.0/gems/activesupport-5.2.4.1/lib/active_support/notifications.rb:170:in `instrument'
app/lib/request_pool.rb:107:in `block in with'
app/lib/connection_pool/shared_connection_pool.rb:21:in `block (2 levels) in with'
app/lib/connection_pool/shared_connection_pool.rb:20:in `handle_interrupt'
app/lib/connection_pool/shared_connection_pool.rb:20:in `block in with'
app/lib/connection_pool/shared_connection_pool.rb:16:in `handle_interrupt'
app/lib/connection_pool/shared_connection_pool.rb:16:in `with'
app/lib/request_pool.rb:106:in `with'
app/workers/activitypub/delivery_worker.rb:46:in `block in perform_request'
vendor/bundle/ruby/2.7.0/gems/stoplight-2.2.0/lib/stoplight/light/runnable.rb:51:in `run_code'
vendor/bundle/ruby/2.7.0/gems/stoplight-2.2.0/lib/stoplight/light/runnable.rb:42:in `run_yellow'
vendor/bundle/ruby/2.7.0/gems/stoplight-2.2.0/lib/stoplight/light/runnable.rb:24:in `run'
app/workers/activitypub/delivery_worker.rb:57:in `perform_request'
app/workers/activitypub/delivery_worker.rb:25:in `perform'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/processor.rb:192:in `execute_job'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/processor.rb:165:in `block (2 levels) in process'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/middleware/chain.rb:128:in `block in invoke'
vendor/bundle/ruby/2.7.0/gems/nsa-0.2.7/lib/nsa/collectors/sidekiq.rb:31:in `block in call'
vendor/bundle/ruby/2.7.0/gems/nsa-0.2.7/lib/nsa/statsd/publisher.rb:27:in `statsd_time'
vendor/bundle/ruby/2.7.0/gems/nsa-0.2.7/lib/nsa/collectors/sidekiq.rb:30:in `call'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/middleware/chain.rb:130:in `block in invoke'
app/lib/sidekiq_error_handler.rb:5:in `call'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/middleware/chain.rb:130:in `block in invoke'
vendor/bundle/ruby/2.7.0/gems/scout_apm-2.3.0.pre3/lib/scout_apm/background_job_integrations/sidekiq.rb:69:in `call'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/middleware/chain.rb:130:in `block in invoke'
vendor/bundle/ruby/2.7.0/gems/sidekiq-unique-jobs-6.0.18/lib/sidekiq_unique_jobs/server/middleware.rb:29:in `call'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/middleware/chain.rb:130:in `block in invoke'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/middleware/chain.rb:133:in `invoke'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/processor.rb:164:in `block in process'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/processor.rb:137:in `block (6 levels) in dispatch'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/job_retry.rb:109:in `local'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/processor.rb:136:in `block (5 levels) in dispatch'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/rails.rb:43:in `block in call'
vendor/bundle/ruby/2.7.0/gems/activesupport-5.2.4.1/lib/active_support/execution_wrapper.rb:87:in `wrap'
vendor/bundle/ruby/2.7.0/gems/activesupport-5.2.4.1/lib/active_support/reloader.rb:73:in `block in wrap'
vendor/bundle/ruby/2.7.0/gems/activesupport-5.2.4.1/lib/active_support/execution_wrapper.rb:87:in `wrap'
vendor/bundle/ruby/2.7.0/gems/activesupport-5.2.4.1/lib/active_support/reloader.rb:72:in `wrap'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/rails.rb:42:in `call'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/processor.rb:132:in `block (4 levels) in dispatch'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/processor.rb:250:in `stats'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/processor.rb:127:in `block (3 levels) in dispatch'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/job_logger.rb:8:in `call'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/processor.rb:126:in `block (2 levels) in dispatch'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/job_retry.rb:74:in `global'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/processor.rb:125:in `block in dispatch'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/logging.rb:48:in `with_context'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/logging.rb:42:in `with_job_hash_context'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/processor.rb:124:in `dispatch'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/processor.rb:163:in `process'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/processor.rb:83:in `process_one'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/processor.rb:71:in `run'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/util.rb:16:in `watchdog'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/util.rb:25:in `block in safe_thread'
```

```
WARN: Stoplight::Error::RedLight: https://example.com/inbox
WARN: vendor/bundle/ruby/2.7.0/gems/stoplight-2.2.0/lib/stoplight/light/runnable.rb:46:in `run_red'
vendor/bundle/ruby/2.7.0/gems/stoplight-2.2.0/lib/stoplight/light/runnable.rb:25:in `run'
app/workers/activitypub/delivery_worker.rb:57:in `perform_request'
app/workers/activitypub/delivery_worker.rb:25:in `perform'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/processor.rb:192:in `execute_job'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/processor.rb:165:in `block (2 levels) in process'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/middleware/chain.rb:128:in `block in invoke'
vendor/bundle/ruby/2.7.0/gems/nsa-0.2.7/lib/nsa/collectors/sidekiq.rb:31:in `block in call'
vendor/bundle/ruby/2.7.0/gems/nsa-0.2.7/lib/nsa/statsd/publisher.rb:27:in `statsd_time'
vendor/bundle/ruby/2.7.0/gems/nsa-0.2.7/lib/nsa/collectors/sidekiq.rb:30:in `call'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/middleware/chain.rb:130:in `block in invoke'
app/lib/sidekiq_error_handler.rb:5:in `call'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/middleware/chain.rb:130:in `block in invoke'
vendor/bundle/ruby/2.7.0/gems/scout_apm-2.3.0.pre3/lib/scout_apm/background_job_integrations/sidekiq.rb:69:in `call'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/middleware/chain.rb:130:in `block in invoke'
vendor/bundle/ruby/2.7.0/gems/sidekiq-unique-jobs-6.0.18/lib/sidekiq_unique_jobs/server/middleware.rb:29:in `call'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/middleware/chain.rb:130:in `block in invoke'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/middleware/chain.rb:133:in `invoke'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/processor.rb:164:in `block in process'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/processor.rb:137:in `block (6 levels) in dispatch'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/job_retry.rb:109:in `local'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/processor.rb:136:in `block (5 levels) in dispatch'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/rails.rb:43:in `block in call'
vendor/bundle/ruby/2.7.0/gems/activesupport-5.2.4.1/lib/active_support/execution_wrapper.rb:87:in `wrap'
vendor/bundle/ruby/2.7.0/gems/activesupport-5.2.4.1/lib/active_support/reloader.rb:73:in `block in wrap'
vendor/bundle/ruby/2.7.0/gems/activesupport-5.2.4.1/lib/active_support/execution_wrapper.rb:87:in `wrap'
vendor/bundle/ruby/2.7.0/gems/activesupport-5.2.4.1/lib/active_support/reloader.rb:72:in `wrap'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/rails.rb:42:in `call'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/processor.rb:132:in `block (4 levels) in dispatch'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/processor.rb:250:in `stats'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/processor.rb:127:in `block (3 levels) in dispatch'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/job_logger.rb:8:in `call'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/processor.rb:126:in `block (2 levels) in dispatch'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/job_retry.rb:74:in `global'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/processor.rb:125:in `block in dispatch'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/logging.rb:48:in `with_context'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/logging.rb:42:in `with_job_hash_context'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/processor.rb:124:in `dispatch'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/processor.rb:163:in `process'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/processor.rb:83:in `process_one'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/processor.rb:71:in `run'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/util.rb:16:in `watchdog'
vendor/bundle/ruby/2.7.0/gems/sidekiq-5.2.7/lib/sidekiq/util.rb:25:in `block in safe_thread'
```

* Add request pool to improve delivery performance

Fix #7909

* Ensure connection is closed when exception interrupts execution

* Remove Timeout#timeout from socket connection

* Fix infinite retrial loop on HTTP::ConnectionError

* Close sockets on failure, reduce idle time to 90 seconds

* Add MAX_REQUEST_POOL_SIZE option to limit concurrent connections to the same server

* Use a shared pool size, 512 by default, to stay below open file limit

* Add some tests

* Add more tests

* Reduce MAX_IDLE_TIME from 90 to 30 seconds, reap every 30 seconds

* Use a shared pool that returns preferred connection but re-purposes other ones when needed

* Fix wrong connection being returned on subsequent calls within the same thread

* Reduce mutex calls on flushes from 2 to 1 and add test for reaping

HTTP 401 responses returned by Mastodon's inbox controller may
be temporary if, for instance, the requesting user's actor/key json
could not be retrieved in a timely fashion. This changes allow retries
instead of dropping the message entirely.

Also added HTTP 408 as that error is by nature temporary.

* If an Update is signed with known key, skip re-following procedure

Because it means the remote actor did *not* lose their database

* Add CLI method for rotating keys

    bin/tootctl accounts rotate [USERNAME]

Generates a new RSA key per account and sends out an Update activity
signed with the old key.

* Key rotation: Space out Update fan-outs every 5 minutes per 1000 accounts

* Skip suspended accounts in key rotation

* Do not raise delivery failure on 4xx errors, increase stoplight threshold

Stoplight failure threshold from 3 to 10
Status code 429 will raise a failure/get retried

* Oops

HTTP connections must be explicitly closed in many cases, and letting
perform method close connections makes its callers less redundant and
prevent them from forgetting to close connections.

Currently, Mastodon will retry delivering toots for a bit over 1 hour.
This is a very short timespan when considering private and direct toots, which
cannot be seen by the recipient at all after the delivery attempts have failed.

Ideally, private and direct toots should have a different number of retries,
but I do not know how to do that.

* Close connection when succeeded posting

* Update webmock

- A successful delivery cancels it out
- An incoming delivery from account of the inbox cancels it out

* Deliver ActivityPub Like

* Deliver ActivityPub Undo-Like

* Deliver ActivityPub Create/Announce activities

* Deliver ActivityPub creates from mentions

* Deliver ActivityPub Block/Undo-Block

* Deliver ActivityPub Accept/Reject-Follow

* Deliver ActivityPub Undo-Follow

* Deliver ActivityPub Follow

* Deliver ActivityPub Delete activities

Incidentally fix #889

* Adjust BatchedRemoveStatusService for ActivityPub

* Add tests for ActivityPub workers

* Add tests for FollowService

* Add tests for FavouriteService, UnfollowService and PostStatusService

* Add tests for ReblogService, BlockService, UnblockService, ProcessMentionsService

* Add tests for AuthorizeFollowService, RejectFollowService, RemoveStatusService

* Add tests for BatchedRemoveStatusService

* Deliver updates to a local account to ActivityPub followers

* Minor adjustments