Enable "chromium.resultdb.result_sink" experiment on chromium try builders at 50%

Bug: 1108016
Change-Id: I5f9bfafea7576c645007ca6c7ec7958d90f6b3fe
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2523064Reviewed-by: Garrett Beaty <gbeaty@chromium.org>
Commit-Queue: Chan Li <chanli@chromium.org>
Cr-Commit-Position: refs/heads/master@{#825898}

infra/config/lib/try.star

@@ -161,9 +161,9 @@ def try_builder(
     if not branches.matches(branch_selector):
         return
 
-    # Enable "chromium.resultdb.result_sink" on try builders at 10%.
+    # Enable "chromium.resultdb.result_sink" on try builders at 50%.
     experiments = experiments or {}
-    experiments.setdefault("chromium.resultdb.result_sink", 10)
+    experiments.setdefault("chromium.resultdb.result_sink", 50)
 
     merged_resultdb_bigquery_exports = [
         resultdb.export_test_results(