Adjust CQ config for luci.infra.try -> luci.infra.depot_tools.try bucket move

See https://chromium-review.googlesource.com/c/565402/ for context.

Bug: 644609
Change-Id: I8edacafdb3bc969e3d0d2fb4589b3ba3fcf9f5d6
Reviewed-on: https://chromium-review.googlesource.com/565412Reviewed-by: Sergiy Byelozyorov <sergiyb@chromium.org>
Commit-Queue: Paweł Hajdan Jr. <phajdan.jr@chromium.org>

infra/config/cq.cfg

@@ -23,12 +23,8 @@ verifiers {
 
   try_job {
     buckets {
-      name: "luci.infra.try"
+      name: "luci.infra.depot_tools.try"
       builders { name: "Depot Tools Presubmit" }
-      builders {
-        name: "Recipe Roll Downstream Tester"
-        experiment_percentage: 100
-      }
     }
   }
 }