Add linux_chromium_clobber_deterministic CQ experiment 1%

This is for the LUCI migration of this builder; the expected
effect of this as far as I understand is that it will cause
1% of CQ runs to include this builder (as an experimental
builder so failure won't block).

No-Try: True
Bug: 731426
Change-Id: I5922b8673481cdd34102e239b3255d5f24423327
Reviewed-on: https://chromium-review.googlesource.com/966700Reviewed-by: Andrii Shyshkalov <tandrii@chromium.org>
Commit-Queue: Quinten Yearsley <qyearsley@chromium.org>
Cr-Commit-Position: refs/heads/master@{#544134}

infra/config/branch/cq.cfg

@@ -117,6 +117,12 @@ verifiers {
         name: "linux_chromium_rel_ng"
         equivalent_to { bucket: "luci.chromium.try" percentage: 100 }
       }
+      builders {
+        # Temporary addition to gather data for LUCI migration.
+        # https://crbug.com/731426
+        name: "linux_chromium_clobber_deterministic"
+        experiment_percentage: 1
+      }
     }
     buckets {
       name: "master.tryserver.chromium.mac"