A second gitlab VM for codfw has been created in T285456.
To make it an actual replica and test restore from backup for T285867, we need to reserve a service IP (v4 and v6) in netbox and give it a DNS name like "gitlab-replica.wikimedia.org" (similar to gerrit-replica.wikimedia.org).
https://gerrit.wikimedia.org/r/c/operations/puppet/+/702123/ made it possible to assign a different service IP per DC, so the new IP needs to be added to hieradata/common/codfw and then puppet will add it to the interface.
This requires putting the gitlab role on the machine that is for now using "insetup".