Don't kill apps that are multi-user aware...

... when looking for background user apps that hold RECORD_AUDIO
permission.

On switching users, we kill any apps that might potentially be
recording audio. But we don't want to kill critical apps that need
to stay running because of multi-user aware services.

Bug: 22564430
Change-Id: I6d9a684d4e044cc3018f0f8181a44aa143a3baeb