Conpherence - use new getDisplayTitle for search results

Summary: Fixes T8066. These search results were using getDisplayData but only need a title. Use more granular API introduced in rPf311f3f910e31b72345e37bf2e5bea0f278fd111.

Test Plan: ran a conpherence query for messages and no more fatal

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin, epriestley

Maniphest Tasks: T8066

Differential Revision: https://secure.phabricator.com/D12719