This CL fixes a failed DCHECK due to incorrect heap capacity.

Also skips three new tests that create multiple isolates.

Bug: v8:11641
Change-Id: I1061b3370efbe2b272bd490705fc728d6bb26910
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2896644
Auto-Submit: Wenyu Zhao <wenyu.zhao@anu.edu.au>
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74583}