Remove "phd.pid-directory" configuration and stop passing "piddir" to daemons
Summary: Ref T13321. The daemons no longer write PID files, so we no longer need to pass any of this stuff to them.
Test Plan: Grepped for affected symbols.
Reviewed By: amckinley
Maniphest Tasks: T13321
Differential Revision: https://secure.phabricator.com/D20608