Re-enable `chromium.resultdb.result_sink` experiment on chromium fyi builders at 30%

Bug: 1108016
Change-Id: I90beaf78f9f4b8508f6229b17b07a44943f442d6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2462049Reviewed-by: Takuto Ikuta <tikuta@chromium.org>
Commit-Queue: Chan Li <chanli@chromium.org>
Cr-Commit-Position: refs/heads/master@{#815450}

infra/config/lib/ci.star

@@ -695,7 +695,7 @@ def fyi_builder(
         # TODO(crbug.com/1108016): Move this kwarg to ci.builder(), after
         # ResultSink and result_adapter is confirmed to work.
         experiments = {
-            "chromium.resultdb.result_sink": 0,
+            "chromium.resultdb.result_sink": 30,
         },
         **kwargs
     )