Log VerifyCredentialResponse instead of response code

Make BiometricDeferredQueue#requestHatFromGatekeeperPassword() log the
VerifyCredentialResponse via its toString() method, rather than
retrieving the response code and logging that.  This is in preparation
for removing direct access to the response code.

Bug: 423038471
Test: atest FrameworksServicesTests:com.android.server.locksettings
Flag: EXEMPT refactor
Change-Id: Ic361128a3d43e874d86e35283dc7524ae08ceadc