LSS: pass secret to AuthSecret HAL when no credential

If there was once a credential, a secret will have been enrolled. When
the credential is removed, that secret is still enrolled but still needs
to be derived. This adds that derivation in the case that the secret is
enrolled by the user doesn't have a credential.

Bug: 77942316
Test: runtest frameworks-services -c com.android.server.locksettings.SyntheticPasswordTests
Change-Id: I099a9537ab0739830a234b5f4f3721f4e8476571