Fixed crash due to incorrect string construction (ros-navigation#5606)

Signed-off-by: Jay Herpin <jherpin@metalsharkboats.com>

Author: JayHerpin

nav2_behavior_tree/include/nav2_behavior_tree/bt_service_node.hpp

@@ -69,9 +69,8 @@ class BtServiceNode : public BT::ActionNodeBase
         node_->get_logger(), "\"%s\" service server not available after waiting for %.2fs",
         service_name_.c_str(), wait_for_service_timeout_.count() / 1000.0);
       throw std::runtime_error(
-              std::string(
-                "Service server %s not available",
-                service_name_.c_str()));
+              std::string("Service server ") + service_name_ +
+              std::string(" not available"));
     }
 
     RCLCPP_DEBUG(