CameraService: Enable presubmit unit tests, and fix them

- Add cameraservice_test to presubmit TEST_MAPPING
- Fix broken CameraProviderManager test

Test: Fixed test passes; 'atest' in frameworks/av/services/camera/libcameraservice
   runs the expected test

Change-Id: Ia1ceaf526884325d56f0e273f89220fdb33493dd