Dev/config load cleanup

If you have a user named pgbouncer with a password, that will get overwritten with no password when the admin database is set up.

This is masked by the fact that the userlist file will be reloaded on the first event loop iteration. However, if you're in a high load environment it's possible for a pgbouncer user to try and connect between startup and that first reload.

This fixes both of those issues.