Otherwise, the last tests that ran in a worker keep sitting on their
sigterm handlers without any running processes. This creates
exceptions when workers terminate.

Bug: v8:8292
Change-Id: Iefb9a4a353399c1e3168eae2916e3cedca4e09b3
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2011831Reviewed-by: Tamer Tas <tmrts@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65907}