Custom filters to subwiki remain on the main Wiki after subwiki is deleted

Prerequisites

Being logged as Admin user.

Steps to reproduce:

1. Open 2 separate window: one is the Notification preferences of the current user and the second Wiki Manager
2. Create a new wiki with any name (for instance, test)
3. After the creation job is done, create a custom filter with any settings that will read events of the newly created wiki (see image)
4. Delete created wiki and wait for job completion
5. Refresh first opened window and observe the custom filters section once more

Actual result

It will have a previously created filter that listens to subwiki that no longer exists (see another image).

Expected result

The custom filter doesn't have any filters that were created for the subwiki after that wiki was deleted.