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/process/result.py

@@ -163,7 +163,7 @@ class ResultProcess(multiprocessing.Process):
 
             except queue.Empty:
                 pass
-            except (KeyboardInterrupt, IOError, EOFError):
+            except (KeyboardInterrupt, SystemExit, IOError, EOFError):
                 break
             except:
                 # TODO: we should probably send a proper callback here instead of