[CQ] Temporarily make avx2 trybot experimental.

NOTRY=true
NOPRESUBMIT=true
TBR=tandrii@chromium.org

Bug: chromium:736757
Change-Id: I920eda5c916981d3588fb7346ec4e811dc5112aa
Reviewed-on: https://chromium-review.googlesource.com/548360Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46219}

infra/config/cq.cfg

@@ -38,11 +38,15 @@ verifiers {
         name: "v8_linux64_asan_rel_ng_triggered"
         triggered_by: "v8_linux64_asan_rel_ng"
       }
-      builders { name: "v8_linux64_avx2_rel_ng" }
+      # TODO(machenbach): Reenable when http://crbug.com/736757 is resolved.
       builders {
-        name: "v8_linux64_avx2_rel_ng_triggered"
-        triggered_by: "v8_linux64_avx2_rel_ng"
+        name: "v8_linux64_avx2_rel_ng"
+        experiment_percentage: 100
       }
+      # builders {
+      #   name: "v8_linux64_avx2_rel_ng_triggered"
+      #   triggered_by: "v8_linux64_avx2_rel_ng"
+      # }
       builders { name: "v8_linux64_gcc_compile_dbg" }
       builders { name: "v8_linux64_gyp_rel_ng" }
       builders {