Add linux_chromium_tsan_rel_ng to 10% of CQs.

BUG=672860
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_chromium_tsan_rel_ng

Review-Url: https://codereview.chromium.org/2596533002
Cr-Commit-Position: refs/heads/master@{#441721}

infra/config/cq.cfg

@@ -57,6 +57,10 @@ verifiers {
         experiment_percentage: 100
       }
       builders { name: "linux_chromium_rel_ng" }
+      builders {
+        name: "linux_chromium_tsan_rel_ng"
+        experiment_percentage: 10
+      }
     }
     buckets {
       name: "master.tryserver.chromium.mac"