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

Re-enable the experiment on try builders, because:
- led issue (crbug.com/1141272) has been fixed
- 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: I9cacc5da63f4197ce6c22d9fa3181ee65375e14c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2521834


Reviewed-by: Ben Pastene <bpastene@chromium.org>
Commit-Queue: Chan Li <chanli@chromium.org>
Cr-Commit-Position: refs/heads/master@{#824560}