Bug: Duplicate items on watchlist

Watchlist was not always being detected correctly, causing beta labs to
not call RecentChangesQuery::isRecordHidden. Patch utilizes the recently
added ChangesList::isWatchlist method to detect when watchlist is being
rendered.

Bug: 71619
Change-Id: I6c7473afdddbcbcf0dd8e5d7949d718e5062661f
Merge "Bug: Duplicate items on watchlist"