R1:03092ca42202

Removed unused loadGitLocalRefs() from PhabricatorRepositoryPullEngine

Summary:
rP2b0ad243d179f81baad24ccd9748a4ba59017d25 introduced `private function loadGitLocalRefs()`.
In rPe910c76e65e54a439a0af4735ae89c70076673d5, the only call to `loadGitLocalRefs()` was removed, using `loadGitRemoteRefs()` to load (and compare) both remote and local refs. Thus remove this unused method.

Test Plan: Read/grep the code in `PhabricatorRepositoryPullEngine`.

Reviewers: O1 Blessed Committers, valerio.bozzolan…