Investigate a failed rollback for the Kubernetes Container Registry deployment

In a recent incident: #661 (closed) the deploy for the gitlab helm chart had failed and attempted a rollback. Despite the note of a successful rollback, we were still left in a degraded state. Utilize this issue to determine what happened:

1. What signaled the failed deploy
2. Why was the Container Registry still down after the rollback

Target job: https://ops.gitlab.net/gitlab-com/gl-infra/k8s-workloads/gitlab-com/-/jobs/885131

Things to look into

1. See if we can determine a diff between the stored versions of helm deployments
   • In this case, gitlab.v26 and gitlab.v27
2. Determine if there was a change which might have impacted the Google Load Balancer associated with the Container Registry service