Rename ERROR to OTHER_ERROR in VerifyCredentialResponse

In preparation for introducing additional error response codes, rename
the existing ERROR response code to OTHER_ERROR.  The new name more
clearly reflects that it's a catch-all for errors that aren't covered by
another response code, whether RETRY or one of the upcoming new ones.

Keep the fromError() method for now, since it is still used.

Test: atest FrameworksServicesTests:com.android.server.locksettings
Bug: 395976735
Flag: EXEMPT refactor
Change-Id: I696ce747d6ca8130a4360e02affc850a6d17d97e