TargetableEvents are not discarded when Event type is switched off

Reproduction step:
1. Create an user, go to the notification settings and switch off Mentions
2. Log in with admin, edit a page to mention the user
3. Log in with the first user

Expected result:

• The created user shouldn't have any notification

Obtained result:

• The user got a notification even if the Mention notification are switched off for him.

Note that it doesn't work for other kind of notifications such as page update/create/delete/comment etc.
Also note that the same problem occurs for specific filters such as shown in XWIKI-17657 (only for 12.6+)