Improve handle loading semantics for tokenizers

Summary:
Ref T7689. Fixes T7688. When there are a bunch of tokenizers with different values of the same object type (e.g. 5 tokenizers with users a, b, c, d, e) we currently issue 5 separate queries to load their handles.

Improve this behavior in the common case so we can usually batch these loads.

Test Plan:

• In Maniphest, set the various search fields to different values.
• Used DarkConsole to examine query plan.
• Saw fewer queries after patch than before.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T7688, T7689

Differential Revision: https://secure.phabricator.com/D12261