Specs for cleanup workers (#3235)

* Add spec files for feed and media cleanup workers

* Add coverage for feed and media cleanup schedulers

* Clean up feed and media cleanup workers

app/workers/scheduler/media_cleanup_scheduler.rb

@@ -12,6 +12,6 @@ class Scheduler::MediaCleanupScheduler
   private
 
   def unattached_media
-    MediaAttachment.reorder(nil).where(status_id: nil).where('created_at < ?', 1.day.ago)
+    MediaAttachment.reorder(nil).unattached.where('created_at < ?', 1.day.ago)
   end
 end