Remove useless notifications

[elvey]

I'm frustrated every few days when I open a useless notification from the communitynotes system.

X should un-send notifications from the communitynotes system once no action is needed:

1. The user has already voted on the note. (Admittedly, re-opening it is user error; an alternative solution for this sub-issue would be to make it easier to differentiate read from unread notifications.)
2. The relevant tweet has been deleted or hidden.

Screenshot of 2:

[y7aa]