fix: Automatically remove expired story mention (#5300)

When a user mentions the connected Instagram page in a story, the story's content is downloaded in Chatwoot, then if the user deletes the story, the content persists in the platform.

fixes: #5258

app/models/concerns/message_filter_helpers.rb

@@ -16,4 +16,8 @@ module MessageFilterHelpers
   def email_reply_summarizable?
     incoming? || outgoing? || input_csat?
   end
+
+  def instagram_story_mention?
+    inbox.instagram? && try(:content_attributes)[:image_type] == 'story_mention'
+  end
 end