Enable "chromium.resultdb.result_sink" experiment on chromium ci builders at 10%

web test runner/sink integration makes blink_web_tests on win builders slow issue (crbug.com/1141606) has been worked around - now blink_web_tests are handled be result_adapter.

Bug: 1108016
Change-Id: I33ac36954db3ef54c4d99327508536b763129205
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2521847Reviewed-by: Ben Pastene <bpastene@chromium.org>
Commit-Queue: Chan Li <chanli@chromium.org>
Cr-Commit-Position: refs/heads/master@{#824693}

infra/config/lib/ci.star

@@ -396,9 +396,9 @@ def ci_builder(
     ]
     merged_resultdb_bigquery_exports.extend(resultdb_bigquery_exports or [])
 
-    # Disable "chromium.resultdb.result_sink" on all ci builders.
+    # Enable "chromium.resultdb.result_sink" on ci builders at 10%.
     experiments = experiments or {}
-    experiments.setdefault("chromium.resultdb.result_sink", 0)
+    experiments.setdefault("chromium.resultdb.result_sink", 10)
 
     # Define the builder first so that any validation of luci.builder arguments
     # (e.g. bucket) occurs before we try to use it