Accessibility layer in inconsistent state after running UI test automation tests.

1. The accessibility layer has a back door for a UI test automation code running
   from the shell to attach. The unregister code does an incorrect identity check
   and as a result the register UI test automation service is not disconnected
   until its process is killed. The fix is super safe and simple.

bug:7409261

Change-Id: I4b1da18be6c5619dadd4a58fca6724529bc59dea