Decrease amount of getAuthenticatorId invocations to the HAL

The HIDL contract is to update the authenticatorID when a new template
is enrolled. Thus, only update the authenticatorId cache when

1) the user is actually switching, which is infrequent
2) a user has enrolled a new biometric

Fixes: 133578311

Test: Authenticator ID is updated when new enrollment occurs
Change-Id: If79cb43ac1f42676995c955203653cb5fae0f10f