This skips the top outliers in debug mode and marks other tests as
slow that frequently flakily time out, see bug.

No=Try: true

Bug: v8:10909
Change-Id: I26b22cceba4a93496f340fe25af0685391fa762b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2407897
Commit-Queue: Maya Lekova <mslekova@chromium.org>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Auto-Submit: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69865}