2/n: Update BiometricService with cleaner lifecycle

Hiding of the BiometricDialog is (almost) all handled by SystemUI now.
BiometricService should only send results to the client when it receives
onDialogDismissed() from SystemUI

Bug: 135082347

Test: atest BiometricServiceTest
Change-Id: Ie91fd54680b942e421b7e187f1107ef7323ea719