Destroy NotificationRequests that are dismissed (#31008)

app/models/notification_request.rb

@@ -9,12 +9,13 @@
 #  from_account_id     :bigint(8)        not null
 #  last_status_id      :bigint(8)
 #  notifications_count :bigint(8)        default(0), not null
-#  dismissed           :boolean          default(FALSE), not null
 #  created_at          :datetime         not null
 #  updated_at          :datetime         not null
 #
 
 class NotificationRequest < ApplicationRecord
+  self.ignored_columns += %w(dismissed)
+
   include Paginable
 
   MAX_MEANINGFUL_COUNT = 100
@@ -34,8 +35,6 @@ class NotificationRequest < ApplicationRecord
   end
 
   def reconsider_existence!
-    return if dismissed?
-
     prepare_notifications_count
 
     if notifications_count.positive?