Remove "PhutilDaemonOverseer->findRunningDaemons()"
Summary: Ref T13321. This was obsoleted by "PhutilProcessQuery" in D20600, and the only callsite was removed in D20601.
Test Plan: Grepped for findRunningDaemons().
Reviewers: amckinley
Reviewed By: amckinley
Maniphest Tasks: T13321
Differential Revision: https://secure.phabricator.com/D20603