Use standard handle loading in Releeph

Summary: Ref T3718. Move from unbatched / ad-hoc loading to standard stuff for handles.

Test Plan: Looked at some requests and saw no changes.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T3718

Differential Revision: https://secure.phabricator.com/D8810