[Autofill] Address API feedback

1. Fix lint baseline + Strings constants
2. Expand CREDMAN acronym

Fixes: 379875945
Test: N/A, name changes to constants
Flag: android.service.autofill.autofill_w_metrics
Change-Id: Id62b6a1c62c9d66bdc6430f76ac1034fb2bba5d6