Orbbec driver doesn't respect external namespace

[bmegli]

Launching driver under external namespace

# below is equivalent to using group with ns in extra launchfile
ROS_NAMESPACE="some_namespace" roslaunch orbbec_camera femto_bolt.launch

One ends up with a mix of namespaced and non-namespaced topics

rostopic list
/camera/color/camera_info
/camera/color/image_raw
/camera/depth/camera_info
/camera/depth/image_raw
/camera/ir/camera_info
/camera/ir/image_raw
/rosout
/rosout_agg
/some_namespace/camera/depth/points
/some_namespace/camera/gyro_accel/sample
/tf
/tf_static