Remove executor cancel from close

Author: NoahStapp

pymongo/periodic_executor.py

@@ -75,8 +75,6 @@ def close(self, dummy: Any = None) -> None:
         callback; see monitor.py.
         """
         self._stopped = True
-        if self._task is not None:
-            self._task.cancel()
 
     async def join(self, timeout: Optional[int] = None) -> None:
         if self._task is not None: