IdentityCredential test shouldn't be fingerprint-only

1) Use BiometricManager#canAuthenticate(BIOMETRIC_STRONG) instead of
   checking FingerprintManager for enrollments
2) Request BIOMETRIC_STRONG when authenticating

Test: Builds
Bug: 151453267
Change-Id: I16837778ca93d984fdf68e1221a5289bf99c25ac
2 files changed