Use Perfetto's Start/StopBlocking() helpers instead of bespoke
synchronization with semaphores.

Cq-Include-Trybots: luci.v8.try:v8_linux64_perfetto_dbg_ng
Bug: v8:8339
Change-Id: If8266d5fa5e3ff6403b9b2e539ec985bc67fcc90
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1728623
Commit-Queue: Sami Kyöstilä <skyostil@chromium.org>
Commit-Queue: Peter Marshall <petermarshall@chromium.org>
Reviewed-by: Peter Marshall <petermarshall@chromium.org>
Auto-Submit: Sami Kyöstilä <skyostil@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63102}