Load audit requests when querying audits

Summary: Fixes T9434. I'm not sure exactly what changed behavior here, but we need a needAuditRequests().

Test Plan: Ran a query which hit the exception (empty query was good enough, locally), then applied this patch; saw exception go away.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T9434

Differential Revision: https://secure.phabricator.com/D14162