correctly handle term signals

- adhoc now terminates gracefully
- avoid race condition on terminations by ignoring errors if
  worker might have been reaped between checking if active and termination call
- ansible-playbook now properly exits on sigint/term
- adhoc and playbook now give exceptions that we should not normally capture
  and rely on top level finally to reap children
- handle systemexit breaks in workers
- added debug to see at which frame we exit
partial fix for #14346

lib/ansible/executor/task_queue_manager.py

@@ -253,7 +253,10 @@ class TaskQueueManager:
                 rslt_q.close()
                 main_q.close()
                 if worker_prc and worker_prc.is_alive():
-                    worker_prc.terminate()
+                    try:
+                        worker_prc.terminate()
+                    except AttributeError:
+                        pass
 
     def clear_failed_hosts(self):
         self._failed_hosts = dict()