search broker endpoints only by launching DT

ml/thing.py

@@ -392,7 +392,6 @@ def __connect_with_broker(self):
             + BColors.ENDC
             + ": Connect with S3I Broker"
         )
-        self.__endpoint = find_broker_endpoint(self.dir, thing_id=self.thing_id)
         if self.__is_broker_rest:
             self.broker = BrokerREST(token=self.access_token)
 
@@ -418,6 +417,7 @@ def receive():
         else:
             if self.broker is None:
                 # first time to build a broker instance
+                self.__endpoint = find_broker_endpoint(self.dir, thing_id=self.thing_id)
                 self.broker = Broker(
                     auth_form="Username/Password",
                     username=" ",