Rietveld CQ has already been disabled and is no longer supoorted.

TBR=sergiyb@chromium.org

No-Try: True
Bug: chromium:770592
Change-Id: If4411aaf15402b3c6d44fd0a8126d1db2150cb46
Reviewed-on: https://chromium-review.googlesource.com/716838Reviewed-by: Sergiy Byelozyorov <sergiyb@chromium.org>
Commit-Queue: Andrii Shyshkalov <tandrii@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48510}