feat: automatically remove queued messages with stale locks (#2872)

app/lib/message_dequeuer/initial_processor.rb

@@ -29,8 +29,8 @@ module MessageDequeuer
     private
 
     def check_message_exists
-      @queued_message.message
-    rescue Postal::MessageDB::Message::NotFound
+      return if @queued_message.message
+
       log "unqueue because backend message has been removed."
       remove_from_queue
       stop_processing

app/lib/message_dequeuer/single_message_processor.rb

@@ -31,8 +31,8 @@ module MessageDequeuer
     private
 
     def check_message_exists
-      queued_message.message
-    rescue Postal::MessageDB::Message::NotFound
+      return if queued_message.message
+
       log "unqueueing because backend message has been removed"
       remove_from_queue
       stop_processing

app/lib/worker/process.rb

@@ -40,7 +40,8 @@ module Worker
       ProcessMessageRetentionScheduledTask,
       PruneSuppressionListsScheduledTask,
       PruneWebhookRequestsScheduledTask,
-      SendNotificationsScheduledTask
+      SendNotificationsScheduledTask,
+      TidyQueuedMessagesTask
     ].freeze
 
     # @param [Integer] thread_count The number of worker threads to run in this process