ci: Suppress cmake.org html documentation search results for index entries

Since Sphinx 5.2.0, the generated html search page reports all index
entries that match a query term.  Unfortunately even non-main entries
get a high score, placing them before more important search results
such as document titles and domain object names.

Work around this for documentation published on `cmake.org` by removing
the logic from `searchtools.js` in the generated html documentation.

Issue: #25175