[FIX] trackers: Get real language pref for watcher, or use site default if ot set (previous similar fix was for simpleEmail mode only)

git-svn-id: file:///var/local/code.tiki.org/tikisvn/branches/12.x@49101 b456876b-0849-0410-b77d-98878d47e9d5
[MRG] Automatic merge, branches/12.x 49090 to 49101

git-svn-id: file:///var/local/code.tiki.org/tikisvn/trunk@49102 b456876b-0849-0410-b77d-98878d47e9d5