* Update plugins/singleusergroup from branch 'master'
- Actually remove Buck based build
Accidentaly, the wrong file was removed. It was supposed to remove BUCK
and not BUILD.
This partially reverts commit 6800d41177013999c7259b387314d812cb51bcce.
Change-Id: Ia131c160a614b7d6dae242def0ace2203dde1230