[CQ] Raise node-integration experiment percentage to 20

Bug: v8:6154
NOTRY=true
TBR=yangguo@chromium.org

Change-Id: I7acb31abd5571261740fd95eeb58f104c26b192e
Reviewed-on: https://chromium-review.googlesource.com/468807Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44403}

infra/config/cq.cfg

@@ -34,7 +34,7 @@ verifiers {
       builders { name: "v8_android_arm_compile_rel" }
       builders {
         name: "v8_node_linux64_rel"
-        experiment_percentage: 10
+        experiment_percentage: 20
       }
       builders { name: "v8_linux64_asan_rel_ng" }
       builders {