Remove background microphone and camera from public api

Also make them ungrantable. These permissions only exist so that
RECORD_AUDIO and CAMERA are true foreground permissions.

Test: atest CtsPermission{1,3}TestCases
      Attempt to grant the permissions
Bug: 158311343
Change-Id: I383883a67acee9a0fb4ade5ca34092c29f8ac254