R1:706c21375e8f

Remove empty implementations of `describeAutomaticCapabilities()`

Summary:
This has been replaced by `PolicyCodex` after D16830. Also:

- Rebuild Celerity map to fix grumpy unit test.
- Fix one issue on the policy exception workflow to accommodate the new code.

Test Plan:
- `arc unit --everything`
- Viewed policy explanations.
- Viewed policy errors.

Reviewers: chad

Reviewed By: chad

Subscribers: hach-que, PHID-OPKG-gm6ozazyms6q6i22gyam

Differential Revision: https://secure.phabricator.