beta: update mwdeploy sudo grants

Deployers were granted rights to (re)start the hhvm fcgi process in
I60115d46aa9329966908a9216361e45acdedf4bd. This will become a part of
scap in Idc01b17ca52922cc71c5e04260c3c098317f6496, so the mwdeploy user
in beta needs to be able to do this action as well.

Change-Id: Idaf199034b3a812dadcac4075f590de9aaf24261