Example launch file needs /robot_description to run on Jazzy

[zimmerman-pliant]

I believe ros2_control has deprecated passing robot_description as a launch-time parameter and instead controller_manager expects to subscribe to the /robot_description topic.

The docs here suggest it was deprecated in Humble:

https://docs.ros.org/en/humble/p/controller_manager/doc/userdoc.html

• Deprecated here? [CM] Use robot_description topic instead of parameter and don't crash on empty URDF 🦿 ros-controls/ros2_control#940
• Removed here? [CM] Remove support for the description parameter and use only robot_description topic ros-controls/ros2_control#1358

I'm running Jazzy and controller_manager just waits for /robot_description:

[ros2_control_node-1] [WARN] [1781635169.176350110] [controller_manager]: Waiting for data on 'robot_description' topic to finish initialization
[ros2_control_node-1] [WARN] [1781635170.176162010] [controller_manager]: Waiting for data on 'robot_description' topic to finish initialization