[test] Better finish terminating workers

A call to cancel_join_thread() is removed as it is suspected to leave
the done_queue with garbled data on process join.

Bug: v8:13113
Change-Id: I85a736cee98d1c2a315efdd468cde216ad848c99
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3891251Reviewed-by: Liviu Rau <liviurau@google.com>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/main@{#83132}

tools/testrunner/local/pool.py

@@ -93,11 +93,6 @@ def Worker(fn, work_queue, done_queue,
       except Exception as e:
         logging.exception('Unhandled error during worker execution.')
         done_queue.put(ExceptionResult(e))
-    # When we reach here on normal tear down, all items have been pulled from
-    # the done_queue before and this should have no effect. On fast abort, it's
-    # possible that a fast worker left items on the done_queue in memory, which
-    # will never be pulled. This call purges those to avoid a deadlock.
-    done_queue.cancel_join_thread()
   except KeyboardInterrupt:
     assert False, 'Unreachable'