[CQ] Add jumbo builder to CQ experiment

NOTRY=true
TBR=sergiyb@chromium.org

Bug: v8:7339
Change-Id: Ia49def6489e8e223b6b1f34657a6d38ae81aece5
Reviewed-on: https://chromium-review.googlesource.com/975129Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52142}

infra/config/cq.cfg

@@ -32,6 +32,10 @@ verifiers {
       }
       builders { name: "v8_linux64_gcc_compile_dbg" }
       builders { name: "v8_linux64_rel_ng" }
+      builders {
+        name: "v8_linux64_jumbo_compile_rel"
+        experiment_percentage: 10
+      }
       builders {
         name: "v8_linux64_rel_ng_triggered"
         triggered_by: "v8_linux64_rel_ng"