Enable the CredentialManager Registry API

We cannot change the flag that this is using, so abandon it entirely and
turn it on the registry all the time.

Bug: 289435946
Test: local
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:d0b8f0a90f7d91ddee515d58da2f34f1d586c7f4)
Merged-In: I7f509eacaf8a973a290f9e429b3705d975bbfccf
Change-Id: I7f509eacaf8a973a290f9e429b3705d975bbfccf