Fix a bad call to "writeInfo()" in "bin/phd stop" with no PHABRICATOR_INSTANCE defined

Summary: See https://discourse.phabricator-community.org/t/phd-status-calls-to-undefined-method-when-theres-no-instance/2918. This call should be logInfo().

Test Plan:

• Purged PHABRICATOR_INSTANCE from my environment. In a Phacility development environment, it comes from loading services/.
• Ran bin/phd stop with all daemons already stopped.
  • Before: bad call.
  • After: helpful error.
• Ran some other bin/phd start, bin/phd status, etc., to kick the tires.
• Grepped for remaining writeInfo() calls (found none).

Reviewers: amckinley

Reviewed By: amckinley

Differential Revision: https://secure.phabricator.com/D20649