Remove nexus_robot_controller

[Yadunund]

The nexus_robot_controller package was introduced when we were still using ros2_controls on humble where controller_manager was not implemented as a lifecycle node. In practice, we didn't rely on the lifecycle feature and hence launch files start the upstream controller_manager and no the nexus_robot_controller node.

Since then the controller_manager has been reimplemented as a lifecycle node so there is no need for nexus_robot_controller. See https://github.com/ros-controls/ros2_control/blob/master/controller_manager/CHANGELOG.rst

[koushikcs562]

hello @Yadunund are there any edges cases or legacy setups where nexus_robot_controller might still be needed ?? i was thinking to solve this issue in the method you suggested above and got a small doubt .