R1:bae8a951143a

Continue replacing Commit/Audit status checks with object-based checks

Summary: Ref T13195. See PHI851. Continuing down the path toward replacing these legacy numeric constants with more modern string constants.

Test Plan:
- Raised concern, requested verification, verified.
- Looked at commit hovercard with audit status.
- Viewed header on a commit page.
- (Didn't test the Doorkeeper stuff since it requires linking to Asana and seems unlikely to break.)

Reviewers: amckinley

Reviewed By: amckinley…