Updated the `Gitlab admin` link to get rid of 404 error

Why is this change being made?

The existing link was broken, I'm replacing with the correct, working link.

Author Checklist

• Provided a concise title for the MR
• Added a description to this MR explaining the reasons for the proposed change, per say-why-not-just-what
  • Copy/paste the Slack conversation to document it for later, or upload screenshots. Verify that no confidential data is added.
• Assign reviewers for this change to the correct DRI(s)
  • If the DRI for the page/s being updated isn’t immediately clear, then assign it to one of the people listed in the "Maintained by" section in on the page being edited.
  • If your manager does not have merge rights, please ask someone to merge it AFTER it has been approved by your manager in #mr-buddies.
• If the changes affect team members, or warrant an announcement in another way, please consider posting an update in #whats-happening-at-gitlab linking to this MR.
  • If this is a change that directly impacts the majority of global team members, it should be a candidate for #company-fyi. Please work with internal communications and check the handbook for examples.

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assigned to @spouliquen1

marked the checklist item Provided a concise title for the MR as completed

marked the checklist item Added a description to this MR explaining the reasons for the proposed change, per [say-why-not-just-what][transparency] as completed

marked the checklist item Assign reviewers for this change to the correct DRI(s) as completed

marked the checklist item If the changes affect team members, or warrant an announcement in another way, please consider posting an update in [#whats-happening-at-gitlab][whats-happening-at-gitlab-slack] linking to this MR. as completed

added this merge request to the merge train at position 12

removed this merge request from the merge train because pipeline did not succeed

added this merge request to the merge train at position 6

merged

mentioned in commit 2be2b5a7