This will print the list of processes still running before and after
joining workers during termination. This will help debugging hanging
tests during flake-bisect or with num-fuzzer, which both terminate
on total timeout and currently still sometimes hang without printing
processes.

Bug: v8:8292
Change-Id: I124b65fa35b8d7a6aa198fcf50f2c20df94dc51a
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1735312Reviewed-by: Tamer Tas <tmrts@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63065}