Convert straggling Herald rules to modern revision status constants

Summary:
Ref T2543. These are the last ArcanistDifferentialRevisionStatus callsites.

This removes the very old legacy precommitRevisionStatus field, which has no other readers. This was obsoleted by the CLOSED_FROM_ACCEPTED stuff, but retained for compatibility.

Test Plan:

• Poked these with the test console, although they're a little tricky to be sure about.
• Grepped for ArcanistDifferentialRevisionStatus, no more hits.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T2543

Differential Revision: https://secure.phabricator.com/D18416