Updates Gitlab runner documentation
This branch modifies the documentation around Gitlab runners. With the new prefixed publisher runners, we're now able to make runners namespaced to each team that wants to use this feature.
GitLab (git.doit.wisc.edu) has been upgraded to version 18.2.8. For more, see: https://about.gitlab.com/releases/2025/07/17/gitlab-18-2-released/
This branch modifies the documentation around Gitlab runners. With the new prefixed publisher runners, we're now able to make runners namespaced to each team that wants to use this feature.