Only allow the system to bind to the visual query detection service.

The visual query detection service is an isolated service which we
want to isolate from the rest of the system as much as possible. We
don't want to allow anybody but the system to bind it, not even its
enclosing application.

Bug: 185746653
Test: local
Change-Id: Ia0d99921c0e69081b19c93b2bb2befcdda138081