add S3_OPEN_TIMEOUT environment variable (#12459)

config/initializers/paperclip.rb

@@ -42,7 +42,7 @@ if ENV['S3_ENABLED'] == 'true'
 
     s3_options: {
       signature_version: ENV.fetch('S3_SIGNATURE_VERSION') { 'v4' },
-      http_open_timeout: 5,
+      http_open_timeout: ENV.fetch('S3_OPEN_TIMEOUT'){ '5' }.to_i,
       http_read_timeout: 5,
       http_idle_timeout: 5,
       retry_limit: 0,