FIX: Pull hotlinked images even when edited by system users (#9890)

Previously the pull hotlinked images job was skipped after system edits. This ensured that we never had an infinite loop of system-edit/pull-hotlinked/system-edit/pull-hotlinked etc.

A side effect was that edits made by system for any other reason (e.g. API, removing full quotes) would prevent pulling hotlinked images. This commit removes the system edit check, and replaces it with another method to avoid an infinite job scheduling loop.

lib/cooked_post_processor.rb

@@ -663,12 +663,11 @@ class CookedPostProcessor
   end
 
   def pull_hotlinked_images
+    return if @opts[:skip_pull_hotlinked_images]
     # have we enough disk space?
     disable_if_low_on_disk_space # But still enqueue the job
     # don't download remote images for posts that are more than n days old
     return unless @post.created_at > (Date.today - SiteSetting.download_remote_images_max_days_old)
-    # we only want to run the job whenever it's changed by a user
-    return if @post.last_editor_id && @post.last_editor_id <= 0
     # make sure no other job is scheduled
     Jobs.cancel_scheduled_job(:pull_hotlinked_images, post_id: @post.id)
     # schedule the job