11/n: Remove unnecessary things from BiometricAuthenticator

This interface was created before the existence of BiometricService.
Since the sensor registration, arbitration, etc all exist in
BiometricService layer, most of the things here can be removed and
split into separate classes.

Bug: 157790417
Test: Builds

Change-Id: I91ebc13959943b86b93d4fff46ee99050f2cb7bc