Create a secure place to store helm charts

Problem Description

GitLab.com Cells needs a secure, private location to store prerelease helm charts that's accessible during deployments without depending on GitLab.com availability. It would be wise to not rely on the Dev instance. We should aim for Ops as this instance is more scalable and can handle the added load.

Reference: https://gitlab.com/gitlab-com/gl-infra/gitlab-dedicated/team/-/merge_requests/1262

Solution Description

Configure a private helm chart repository on Ops with proper authentication and automated chart copying from the dev mirror (known as Build).

Exit Criteria

• Private repository configured on GCP Artifact Registry
• Authentication system implemented
• CI job verified for automated chart copying
• Access controls configured and tested
• Documentation completed for repository management