Followup from D11358#106424 and make policy.locked fully work

Summary: Fast commit. Also forgot to make the config override the existing policy. I *think* this is the right spot and we're good? Ref T6947.

Test Plan: viewed the application settings page for people application and saw the correct overrode setting.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin, epriestley

Maniphest Tasks: T6947

Differential Revision: https://secure.phabricator.com/D11373