Use `PhutilConsole` in the `./scripts/daemon/exec/exec_daemon.php` script

Summary: Use `PhutilConsole` instead of `fwrite`.

Test Plan: Is there any reason we can't use `PhutilConsole`?

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D9971