Remove legacy `withStatus()` method from RevisionQuery
Summary: Ref T2543. All callsites are now in terms of `withStatuses()`.
Test Plan:
- Called `differential.query` and `differential.find` from Conduit API.
- Grepped through all `withStatus()` callsites.
Reviewers: chad
Reviewed By: chad
Maniphest Tasks: T2543
Differential Revision: https://secure.phabricator.com/D18396