Properly cancel bugreport notification

Remote bugreport collection notification is posted for UserHandle.ALL,
but is cancelled for user0 (system_server context). As a result the
notification doesn't go away when cancelling. This CL changes it so that
it is cancelled for UserHandle.ALL as well.

Bug: 296321653
Bug: 296321167
Test: CTS Verifier/Device Owner Requesting Bugreport Tests
Change-Id: I02780618584b66f96af907fca0a883f62a9882c0