PYTHON-5073 Convert test.test_connection_monitoring to async

test/asynchronous/pymongo_mocks.py

@@ -66,7 +66,7 @@ def __init__(self, server_description, topology, pool, topology_settings):
     def cancel_check(self):
         pass
 
-    def join(self):
+    async def join(self):
         pass
 
     def open(self):
@@ -75,7 +75,7 @@ def open(self):
     def request_check(self):
         pass
 
-    def close(self):
+    async def close(self):
         self.opened = False