Remove loadMemberPHIDs from PhabricatorProject

Summary:
Ref T603. Move toward stamping out all the Project / ProjectProfile query irregularities with respect to policies.

  - Fixes a bug with Asana publishing when the remote task is deleted.
  - Fixes an issue with Herald commit rules.

Test Plan:
  - Viewed projects;
  - edited projects;
  - added and removed members from projects;
  - republished Asana-bridged feed stories about commits.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T603

Differential Revision: https://secure.phabricator.com/D7251