Update link to Archives

What does this MR do and why?

When older versions move to archives.docs.gitlab.com, the link to the archives page no longer works, as it's a relative link. This link should always point to https://docs.gitlab.com/archives, regardless of where the site is deployed. We want visitors to always see the current state of available archived versions.

Closes #1630 (closed)

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

1. Configure a local GitLab Docs environment: https://gitlab.com/gitlab-org/gitlab-docs/-/blob/main/doc/setup.md.
2. Check out this branch, then view the site: make view
3. Verify that the "Archives" link on the Versions menu takes you to docs.gitlab.com/archives.

Testing on the review app also works! https://remove-archives-link.docs.gitlab-review.app/ee/user/project/repository/

Merge request acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this merge request.