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

TBR=phoglund@chromium.org

No-Try: True
Bug: chromium:770592
Change-Id: I2679e9193dfb5ec751bdc76d35fe5d835b44bd0a
Reviewed-on: https://chromium-review.googlesource.com/714302Reviewed-by: Henrik Kjellander <kjellander@chromium.org>
Commit-Queue: Andrii Shyshkalov <tandrii@chromium.org>