jobs: migrate pool category updates to ActiveJob.

app/jobs/update_pool_pseudo_tags_job.rb

@@ -0,0 +1,8 @@
+class UpdatePoolPseudoTagsJob < ApplicationJob
+  queue_as :default
+  queue_with_priority 20
+
+  def perform(pool)
+    pool.update_category_pseudo_tags_for_posts
+  end
+end

app/models/pool.rb

@@ -291,7 +291,7 @@ class Pool < ApplicationRecord
 
   def update_category_pseudo_tags_for_posts_async
     if saved_change_to_category?
-      delay(:queue => "default").update_category_pseudo_tags_for_posts
+      UpdatePoolPseudoTagsJob.perform_later(self)
     end
   end