[CQ] Add next-gen win-nosnap-shared trybot as experiment

BUG=535160
TBR=sergiyb@chromium.org, kjellander@chromium.org
NOTRY=true
NOPRESUBMIT=true

Review URL: https://codereview.chromium.org/1864963003

Cr-Commit-Position: refs/heads/master@{#35304}

infra/config/cq.cfg

@@ -60,6 +60,10 @@ verifiers {
       }
       builders { name: "v8_win_compile_dbg" }
       builders { name: "v8_win_nosnap_shared_compile_rel" }
+      builders {
+        name: "v8_win_nosnap_shared_rel_ng"
+        experiment_percentage: 30
+      }
       builders { name: "v8_win_rel_ng" }
       builders {
         name: "v8_win_rel_ng_triggered"