Watches of inactive users log errors

When user privileges are revoked (e.g. in external Crowd directory user is removed from the groups synchronised with FishEye) any watches that user has configured are still being processed, but they would cause errors to be logged:

ERROR [FE-WatchChecker ] fisheye DefaultWatchManager$WatchChecker-checkWatchesForRep - Could not create trusted user login for user [46: someuser]. BaseReviewNotification skipped for this user.

Those should not really be errors but debugs.
We don't want obviously to delete watches automatically as that would be irreversible operation, if user was removed from a Crowd group by mistake re-adding him later would not resurrect his/her watches back.