RESTRICT AUTOMERGE Remove ScrimController from BiometricUnlockController

It was unnecessary - the DozeScrimController is enough
to determine whether the device is pulsing.

Test: show a notification (via notify test app) in AoD, then
authenticate from AoD and notice the screen doesn't light up
before transitioning to the home screen.
Bug: 262002530
Bug: 237362467
Change-Id: Ic4c4837cdbe0fbcdcc0d5500a659bdb75b04e848