Release protected PyPI packages feature

What does this MR do and why?

GitLab has developed a new feature to support protected PyPI packages in its PyPI Repository. This feature aims to enhance security and control over package management within GitLab. The feature was gated behind the packages_protected_packages_pypi feature flag. After the feature flag has been enabled globally on gitlab.com without issues, we clean it up in this MR and release the feature.

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.

• Identify packages as protected to prevent accid... (&5574)
• Protected packages: PyPI package push protection (!135475 - merged)

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

N/A

How to set up and validate locally

Related to #494194 (closed)