Clear BiometricScheduler when biometric HAL dies

Operations cannot be expected to complete if the HAL dies. The
easiest solution is to clear any existing operation, as well as
any pending operations.

It's dangerous if we leave pending operations in the queue, since
for some HALs, subsequent operations depend on preceeding operations.
For example, updateActiveUser + authenticate.

Fixes: 172683967
Test: atest com.android.server.biometrics

Change-Id: I50b5234d4b382b08767dc359c4a13404e73897c2