Create runbook for connecting to container registry database
Context
We're working on rolling out the new container registry backed by a metadata database for GitLab.com (gitlab-org&5523 (closed)).
As of today, the new version is only deployed to pre
but the staging database cluster was already provisioned (https://gitlab.com/gitlab-com/gl-infra/infrastructure/-/issues/11294).
Purpose
Create a runbook for connecting to the container registry database, similar to that for Praefect.