Fix the visibility of PhutilDaemon::run methods
Summary: Ref T6822. This method is only called from PhutilDaemon::execute() and can be made protected.
Test Plan: Launched a daemon with ./bin/phd launch.
Reviewers: epriestley, #blessed_reviewers
Reviewed By: epriestley, #blessed_reviewers
Subscribers: Korvin, epriestley
Maniphest Tasks: T6822
Differential Revision: https://secure.phabricator.com/D11404