Remove catan_investigation as a category, because it isn't used

This is an antiquated category, and as it stands, won't be used in the
near future, either.

Change-Id: I027522c910a11a550e6eae7e3db340919626f0fb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4304325


Reviewed-by: Dale Curtis <dalecurtis@chromium.org>
Commit-Queue: Sean Maher <spvw@chromium.org>
Reviewed-by: Stephen Nusko <nuskos@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1112864}