Remove Rietveld CQ config.

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>

infra/config/cq.cfg

@@ -7,16 +7,8 @@ cq_status_url: "https://chromium-cq-status.appspot.com"
 git_repo_url: "https://chromium.googlesource.com/libyuv/libyuv.git"
 
 gerrit {}
-rietveld {
-  url: "https://codereview.chromium.org"
-}
-
 
 verifiers {
-  reviewer_lgtm {
-    committer_list: "project-libyuv-committers"
-    dry_run_access_list: "project-libyuv-tryjob-access"
-  }
   gerrit_cq_ability {
     committer_list: "project-libyuv-committers"
     dry_run_access_list: "project-libyuv-tryjob-access"