Fix slow distinct queries where grouped queries are faster (#15287)

About 2x speed-up on inboxes query

app/controllers/admin/statuses_controller.rb

@@ -14,7 +14,7 @@ module Admin
       @statuses = @account.statuses.where(visibility: [:public, :unlisted])
 
       if params[:media]
-        account_media_status_ids = @account.media_attachments.attached.reorder(nil).select(:status_id).distinct
+        account_media_status_ids = @account.media_attachments.attached.reorder(nil).select(:status_id).group(:status_id)
         @statuses.merge!(Status.where(id: account_media_status_ids))
       end