When not being embedded, there's no need to try to share time with the
embedder.

Additionally, avoid too small step sizes.

Bug: chromium:1044630, chromium:1048631
Change-Id: I227bfd120b5ce1976935d27c2140263f7364eb51
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2036085
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66115}