GitLab.com Container Registry to use Google Cloud CDN

This post details the upcoming change to use Google Cloud CDN for the GitLab.com Container Registry, redirecting blob download and existence check requests from Google Cloud Storage to `cdn.registry.gitlab-static.net`. It outlines the technical mechanism of redirection, the gradual rollout plan, and the impact on users, specifically noting the need to update allow lists for `storage.googleapis.com` to include the new CDN endpoint.