Release protected container repositories feature

Note to maintainers

If the changes look good, could you please approve the MR but DO NOT merge this MR? We are still in the process of gradual rollout of feature flag.

What does this MR do and why?

Release protected container repositories feature

Adds feature to support protected repositories to container registry.

We clean up the feature flag in this MR and release the feature as per #429074

Changelog: added

References

Please include cross links to any resources that are relevant to this MR. This will give reviewers and future readers helpful context to give an efficient review of the changes introduced.

• Change feature name to Container repository pro... (!174147 - merged) • Rahul Chanila • 17.7
• Update REST & GraphQL APIs for protected contai... (!174642 - merged) • Rahul Chanila • 17.7
• Rename filenames for container protection repos... (!176751 - merged) • Rahul Chanila • 17.8

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

Screenshots are required for UI changes, and strongly recommended for all other merge requests.

Before	After

How to set up and validate locally

1. Enable container registry in UI only https://gitlab.com/gitlab-org/gitlab-development-kit/-/blob/main/doc/howto/registry.md#set-up-container-registry-to-display-in-ui-only
2. Visit Project > Settings > Packages and registries
3. Expand Container registry
4. Test protected container repositories functionality.

Related to #480385