Verify token caching

[joshtrichards]

There's chance that caching is being handled in an inconsistent way in the Push class:

• neither of the deletePushToken*() methods directly update the cache; both rely on the caller to handle that
• not all instances where deletePushToken*() methods are called update the cache
• the PushController class has some overlapping functions with Push that do direct DB updates/inserts. That further complicates things.
• the PushController class isn't even aware of the cache used by the Push class

Impact:

• based on the expiration time used for the cache in Push::validateToken() at a minimum it's possible for there to be a discrepancy for re-registered devices of ~10 minutes (I think)
• duplicate code in Push and PushController classes increases code maintenance burden as well as inconsistencies/bugs

Disclaimer: It's possible the cache matter is prevented in some other way; I don't have time to get too deep into this today, but wanted to note it since it seems to be the case.

[nickvergessen]

neither of the deletePushToken*() methods directly update the cache;

The cache in Push is not about the content of the notifications_pushhash table but the authtoken, so purging the cache based on that is not necessary.
Therefore the fact of an updated device is also not "not reflected in the cache"

duplicate code in Push and PushController classes increases code maintenance burden as well as inconsistencies/bugs

While theoretical true, the fact that most of this code is simply unchanged in years makes me thing the opposite here. Changing anything can add maintenance burden and debugging efforts going forward in code that worked for years, e.g. the last actual code change in the PushController was 2021 :P https://github.com/nextcloud/notifications/commits/master/lib/Controller/PushController.php