Exclude embedder tracing time

Bug: chromium:945806
Change-Id: I9719a42f86fd6edad8fd2b0f707b4dc7feada277
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1564437Reviewed-by: Hannes Payer <hpayer@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60783}