Policy - convert Drydock query for repository to policy-based query
Summary: Ref T7094. Switch to OmnipotentUser policy-based query since this is usually done offline, etc.
Test Plan: pretty simple code change so I just have my fingers crossed while I am typing this
Reviewers: epriestley
Reviewed By: epriestley
Subscribers: Korvin, epriestley
Maniphest Tasks: T7094
Differential Revision: https://secure.phabricator.com/D11655