Update bt_service_node.hpp debug msg (#4398)

Provide service_name instead of service_node_name for debugging bt_service_node

Signed-off-by: João Britto <cbn.joao@gmail.com>

Author: joaobrittoneto

nav2_behavior_tree/include/nav2_behavior_tree/bt_service_node.hpp

@@ -85,11 +85,11 @@ class BtServiceNode : public BT::ActionNodeBase
     if (!service_client_->wait_for_service(wait_for_service_timeout_)) {
       RCLCPP_ERROR(
         node_->get_logger(), "\"%s\" service server not available after waiting for 1 s",
-        service_node_name.c_str());
+        service_name_.c_str());
       throw std::runtime_error(
               std::string(
                 "Service server %s not available",
-                service_node_name.c_str()));
+                service_name_.c_str()));
     }
 
     RCLCPP_DEBUG(