Revert of Require recipe tryjob in CQ (patchset #1 id:1 of https://codereview.chromium.org/2157503003/ )

Reason for revert:
Downstream tester messed up now, see https://crbug.com/644609

Original issue's description:
> Require recipe tryjob in CQ
>
> BUG=628801
>
> Committed: ac74456f1e

TBR=phajdan.jr@chromium.org,estaab@chromium.org,iannucci@chromium.org
NOTRY=true
(no try because the tester itself is broken)
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=628801, 644609

Review-Url: https://codereview.chromium.org/2322763002

infra/config/cq.cfg

@@ -21,7 +21,10 @@ verifiers {
     buckets {
       name: "luci.infra.try"
       builders { name: "Depot Tools Presubmit" }
-      builders { name: "Recipe Roll Downstream Tester" }
+      builders {
+        name: "Recipe Roll Downstream Tester"
+        experiment_percentage: 100
+      }
     }
   }
 }