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

This is a reland of 6bcf1a99

Original change's description:
> 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/+/2462049
> Reviewed-by: Takuto Ikuta <tikuta@chromium.org>
> Commit-Queue: Chan Li <chanli@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#815450}

Bug: 1108016
Change-Id: I257a1f13a7cefe4c95e0a93d9ba87b57b19c716f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2463102
Auto-Submit: Chan Li <chanli@chromium.org>
Reviewed-by: Takuto Ikuta <tikuta@chromium.org>
Commit-Queue: Chan Li <chanli@chromium.org>
Cr-Commit-Position: refs/heads/master@{#815483}

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
     )