Replace Gerrit URLs with GitLab URLs
Additionally, update .gitreview so that developers can use gerritlab per https://www.mediawiki.org/wiki/GitLab/Hosting_a_project_on_GitLab#Updating_.gitreview.
Bug: T344733
How to register an account on GitLab. To prevent spam, new accounts are locked until approved by an admin or the approver bot. You can also file an unlock request to expedite access.
Support: mw:GitLab, how to host a project on GitLab, #wikimedia-gitlab on libera.chat, #GitLab on Phabricator.
Additionally, update .gitreview so that developers can use gerritlab per https://www.mediawiki.org/wiki/GitLab/Hosting_a_project_on_GitLab#Updating_.gitreview.
Bug: T344733