Fetch version files from GitLab instead of using main branch

What does this merge request do and why?

Update the process for cloning and compiling binaries for Gitaly and GitLab Shell by using version files from gitlab-org/gitlab. Instead of using the main branch, we now use these files to specify exact versions for cloning or checking out to make sure stable versions are compiled.

Closes #2166 (closed)

How to set up and validate locally

1. Check compile:gitaly job to verify it checks out GITALY_SERVER_VERSION from the version file: https://gitlab.com/gitlab-org/gitlab-development-kit/-/jobs/7848183354#L217.
2. Check compile:gitlab-shell job to verify it clones the repository using the correct tag version: https://gitlab.com/gitlab-org/gitlab-development-kit/-/jobs/7848183348#L193.

Impacted categories

The following categories relate to this merge request:

• gdk-reliability - e.g. When a GDK action fails to complete.
• gdk-usability - e.g. Improvements or suggestions around how the GDK functions.
• gdk-performance - e.g. When a GDK action is slow or times out.

Merge request checklist

• This change is backward compatible. If not, please include steps to communicate to our users.
• Tests added for new functionality. If not, please raise an issue to follow-up.
• Documentation added/updated, if needed.
• Announcement added, if change is notable.
• gdk doctor test added, if needed.
• Add the ~highlight label if this MR should be included in the CHANGELOG.md.