Add breadcrumb trail to search results

What does this MR do and why?

• Adds a breadcrumb trail alongside each search result to provide helpful context to visitors.
• Adjusts the number of results shown (10 => 7).

Closes #1370 (closed)

Screenshots, screen recordings, or links to review app

Before	After

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: https://gitlab.com/gitlab-org/gitlab-docs/-/blob/main/doc/setup.md.
2. Compile with Google search: https://gitlab.com/gitlab-org/gitlab-docs/-/blob/main/doc/search.md#local-build-with-google-programmable-search
3. Run searches from the homepage, an interior page, and the /search page.
4. Verify you can see breadcrumbs alongside results. We verified that the breadcrumbs match the global nav in the previous backend MR.

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.