R1:ecc4c531c9cb

Stop threading handles through the CustomField + ApplicationSearch pipeline

Summary:
Ref T8441. Ref T7715.

- These are obsolete after the Viewer/HandlePool changes.
- These are unused after the typeahead parameterization changes.

Test Plan: `grep`, poked around.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T7715, T8441

Differential Revision: https://secure.phabricator.com/D13176