Theme updates for Hugo v0.148.2

What does this MR do and why?

WHAT

• This MR upgrades Hugo template version from 0.145.0 to 0.148.2.
• Additionally, fixes template logic changes caused by the upgrade.
• Upgraded using the details found here: https://gohugo.io/templates/new-templatesystem-overview/.

WHY

• We want to stay up-to-date with dependencies such as Hugo to avoid any potential bugs/security risks in the future.

Screenshots, screen recordings, or links to review app

No visual changes expected. Simply updating template locations and upgrading our local/build version of Hugo.

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.
2. Check out this branch.
3. Make sure normal make view, make view-archive, and review app builds are normal additionally the site has no errors due to template issues. Also make sure translations work (enable ja-jp in /docs-gitlab-com/config/_default/hugo.yaml).

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.

Closes #350 (closed)