Reduce search engines to 8 for all countries.

UI can only accommodate a maximum of 8 search engines. This CL enforces
this requirement when loading the search engines.

Bug: 331893686

Change-Id: If4c248ce8c09b6b712c72c05df60dc895e7be7f6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5404791


Commit-Queue: Mihai Sardarescu <msarda@chromium.org>
Reviewed-by: Nicolas Dossou-Gbété <dgn@chromium.org>
Auto-Submit: Mihai Sardarescu <msarda@chromium.org>
Commit-Queue: Nicolas Dossou-Gbété <dgn@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1280125}