Improve handle batching behavior for commit list view

Summary: Ref T10978. Handle loads can be batched a bit more efficiently by doing them upfront.

Test Plan: Queries dropped a bit locally, but I mostly have the same autors/auditors. I'm seeing 286 queries on my account in production, so I'll check what happens with that.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T10978

Differential Revision: https://secure.phabricator.com/D17225