Why
* ApiQueryWatchList allows filtering anon users or not-anon users.
It is not obvious wether temporary users should be considered
anon for these purposes.
* The equivalent filters in recent changes group temporary users
with anonymous users (T343322).
* Since ApiQueryWatchlist queries the recentchanges table, and
shares many filters with recent changes, it makes sense to
filter the same way in both, and therefore to group temporary
users with anonymous users.
What
* Update queries in WatchedItemQueryService to group temporary
users with anonymous users for FILTER_ANON and FILTER_NOT_ANON.
* Don't change the 'anon' flag, because the other APIs flag
temporary users with anon=false.
* Instead add a 'temp' flag for temporary users.
Bug: T358693
Change-Id: I4cd3a4d0c5f4f488933cf3f06dee62a9beb85440
0b7a4b049a