replace fixed with derived namespace

src/RobotStateProvider.cpp

@@ -139,7 +139,7 @@ namespace robot_state_provider {
       // get the elements in the group
       for (const auto &group: groups) {
         std::map<std::string, std::string> element_topics{};
-        std::string key{"/panda_mqtt_connector" + elementType + group};
+        std::string key{n.getNamespace() + elementType + group};
         if (!n.getParam(key, element_topics)) {
           ROS_ERROR_STREAM("Unable to retrieve value for " << key);
         }