consider decreasing range of RGBD obstacle layer

[rayvburn]

With a real camera, at approx. 4-5 meters the projected laser scan points start to create false positives of obstacles (especially on the global costmap as local is bounded to 4 meters)

[rayvburn]

In fact, from the very beginning of this package existence, the rgbd_scan configuration limits the obstacle range to 3.5 m (both global_costmap_public_sim.yaml and local_costmap_public_sim.yaml:

    rgbd_scan:
      sensor_frame: base_footprint
      data_type: LaserScan
      topic: rgbd_scan
      expected_update_rate: 0.5
      observation_persistence: 0.0
      inf_is_valid: true
      marking: true
      clearing: true
      raytrace_range: 3.5
      obstacle_range: 3.2
      blanking_range: 0.5
      min_obstacle_height: -0.1
      max_obstacle_height: 0.2
      debug: true

TODO: Evaluate whether this configuration is properly loaded when running the navigation modules on the real robot.