stress: fix regression since monitoring changes in the admin node

Stress code reuses the admin application class and the latter
was changed in commit e434c253.

neo/tests/stress.py

@@ -45,6 +45,7 @@ class Handler(MasterEventHandler):
 
 class StressApplication(AdminApplication):
 
+    backup_dict = {}
     cluster_state = server = uuid = None
     listening_conn = True
     fault_probability = 1
@@ -65,6 +66,9 @@ class StressApplication(AdminApplication):
     def close(self):
         BaseApplication.close(self)
 
+    def updateMonitorInformation(*args, **kw):
+        pass
+
     def run(self):
         visibility = None
         from logging import disable, ERROR