Update CNG project to support internal release notation

Context

There is an emerging need to build and deliver private packages to remediate GitLab Dedicated instances, the internal nature of such packages is required to prevent disclosing the vulnerability and to make it independent from the GitLab patch releases.

The outcome of the tag and tagless investigation showed the CNG project doesn't support an internal notation (17.5.1.internal0) https://gitlab.com/gitlab-com/gl-infra/delivery/-/issues/20504#impact-per-project. This issue aims to adjust the CNG codebase to support internal packages.

Links:

• https://gitlab.com/gitlab-com/gl-infra/delivery/-/issues/20565+
• https://gitlab.com/gitlab-com/gl-infra/delivery/-/issues/20504+
• https://gitlab.com/gitlab-org/distribution/team-tasks/-/issues/1626+

Exit criteria

Collaboration with the Build team (former Distribution) will be required

• Identify the changes required on CNG
• Distribution maintainers are aligned with the required changes
• Update CNG codebase gitlab-org/build/CNG!2117 (merged)
• A test is performed to validate that the CNG project supports internal packages => Follow-up #20783 (closed)