Notifications Watched page/space/wiki switches display as "on" in the case of an exclusive filter unless _all_ events are excluded

By default in XWiki, if a user doesn't watch anything, it's considered that they watch everything. A side-effect of this is that the watch switches are on everywhere.
The usecase I'm trying to implement is to disable this, and not send any notification to a user as long as they haven't suscribed (watched) any page.

Steps to reproduce:

• I'm activating the "page" events
• I'm creating an exclusive filter for the whole wiki, for all the events except for "Mentions".
  • including the mention events in the excluded events here would prevent me from receiving mention notifications, since this is how targetable events work (they're impacted by exclusion filters) and this not what I want
    

Expected result:

• the switches are off on the pages so that I can actually start watching pages to receive notifications for them
  

Actual result:

• the switches are still on for pages, I cannot subscribe to any page, they all appear as watched even if I don't receive any notification
  

I think this behaviour was introduced by XWIKI-17787 .

This issue reproduces exactly the same for a globally set exclusion filter.

The default that everything is watched unless explicitly excluded along with this issue that make exclusions very difficult to use.

See also https://forum.xwiki.org/t/clarify-the-behaviour-of-notification-watch-switches/7471/14 where I mentioned this usecase.