Remove 6 unused watchlist messages

Follows-up r10378 (597ec6c685d8):
* watchmethod-recent
* watchmethod-list

Follows-up r23693 (a4536a5a72b2):
* watchlistcontains
* iteminvalidname

Follows-up r92231 (8c73abd507bf):
* watchlistedit-numitems
* watchlistedit-noitems

Change-Id: I9e4d67c2ea34f1e6dd99f4ea2597abd64bb7281e
Merge "Remove 6 unused watchlist messages"