code format cleanup Watcher model

git-svn-id: http://svn.redmine.org/redmine/trunk@12568 e93f8b46-1217-0410-a6f0-8f06a7374b81
remove unneeded Relation#all from Watcher#prune_single_user

git-svn-id: http://svn.redmine.org/redmine/trunk@12569 e93f8b46-1217-0410-a6f0-8f06a7374b81