[nav2_costmap_2d] Fix obstacle_layer trying to use RELIABLE QoS

Use QoS profile from rclcpp::SensorDataQoS() instead of rmw_qos_profile_t.
This solves an issue where the subscriber uses RELIABLE setting even when initialized from rmw_qos_profile_sensor_data.
In addition the Subscriber(..., rmw_qos_profile_t) constructor is deprecated in favor of Subscriber(..., rclcpp::QoS)

nav2_costmap_2d/plugins/obstacle_layer.cpp

@@ -225,8 +225,7 @@ void ObstacleLayer::onInitialize()
       source.c_str(), topic.c_str(),
       global_frame_.c_str(), expected_update_rate, observation_keep_time);
 
-    rmw_qos_profile_t custom_qos_profile = rmw_qos_profile_sensor_data;
-    custom_qos_profile.depth = 50;
+    const auto custom_qos_profile = rclcpp::SensorDataQoS().keep_last(50);
 
     // create a callback for the topic
     if (data_type == "LaserScan") {