Refine broadcast in commitRollback

Silence qualified user warning by using sendBroadcastAsUser.
The user is UserHandle.SYSTEM.
Limit recievers to those holding MANAGE_ROLLBACKS permission.

Test: warning does not appear in logcat when running atest RollbackTest
Fixes: 128280826
Change-Id: I85b905d2b20f3993859ec87948f309c1934a4a26