Updating last meaningful content update to include default page template and file path

• Please check this box if this contribution uses AI-generated content (including content generated by GitLab Duo features) as outlined in the GitLab DCO & CLA. As a benefit of being a GitLab Community Contributor, you receive complimentary access to GitLab Duo.

Why is this change being made?

Updating some code in relation to MR261 where we added frontmatter support for the date: parameter to show a "Content last updated" status banner.

The partial code was only included on /layouts/docs/list.html but in testing we discovered it also needs to be available on /layouts/_default/content.html (see above photo). During testing it was also discovered that the $historyHref var was pointing to a directory path instead of file path, the code was also adjusted to correctly reflect the file path.

Author and Reviewer Checklist

Please verify the check list and ensure to tick them off before the MR is merged.

• Provided a concise title for this Merge Request (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, and the content is SAFE
• Assign reviewers for this MR to the correct Directly Responsible Individual/s (DRI)
  • The when to get approval handbook section explains the workflow in more detail
• For transparency, share this MR with the audience that will be impacted.
  • Team: For changes that affect your direct team, share in your group Slack channel
  • Department: If the update affects your department, share the MR in your department Slack channel
  • Handbook: For changes that affect handbook users, but does not need company-wide attention, post in the #handbook Slack channel
  • Company: If the update affects all (or the majority of) GitLab team members, post an update in #whats-happening-at-gitlab linking to this MR
    • For high-priority company-wide announcements work with the internal communications team to post the update in #company-fyi and align on a plan to circulate in additional channels like the "While You Were Iterating" Newsletter

/label HandbookOperations /label featureaddition /label typefeature /label workflowin dev