We use project-config for gerrit, gitea and nodepool config. That's
cool, because can clone that from zuul too and make sure that each
prod run we're doing runs with the contents of the patch in question.
Introduce a flag file that can be touched in /home/zuulcd that will
block zuul from running prod playbooks. By default, if the file is
there, zuul will wait for an hour before giving up.
Rename zuulcd to zuul
To better align prod and test, name the zuul user zuul.