Default path to ur_client_library urscript

[livanov93]

PR changes default urscript that is sent to the robot when headless_mode is used.

[fmauch]

That seems not to work for me.

ament_index_python.packages.PackageNotFoundError: "package 'ur_client_library' not found, searching: ['/home/mauch/robot_folders/checkout/ur_ros2_galactic/colcon_ws/install/ur_simulation_gazebo', '/home/mauch/robot_folders/checkout/ur_ros2_galactic/colcon_ws/install/ur_calibration', '/home/mauch/robot_folders/checkout/ur_ros2_galactic/colcon_ws/install/ur_robot_driver', '/home/mauch/robot_folders/checkout/ur_ros2_galactic/colcon_ws/install/ur_controllers', '/home/mauch/robot_folders/checkout/ur_ros2_galactic/colcon_ws/install/ur_msgs', '/home/mauch/robot_folders/checkout/ur_ros2_galactic/colcon_ws/install/ur_moveit_config', '/home/mauch/robot_folders/checkout/ur_ros2_galactic/colcon_ws/install/ur_bringup', '/home/mauch/robot_folders/checkout/ur_ros2_galactic/colcon_ws/install/ur_description', '/home/mauch/robot_folders/checkout/ur_ros2_galactic/colcon_ws/install/ur_dashboard_msgs', '/home/mauch/robot_folders/checkout/ur_ros2_galactic/colcon_ws/install/ros2_control_demos', '/home/mauch/robot_folders/checkout/ur_ros2_galactic/colcon_ws/install/ros2_control_demo_bringup', '/home/mauch/robot_folders/checkout/ur_ros2_galactic/colcon_ws/install/rrbot_description', '/home/mauch/robot_folders/checkout/ur_ros2_galactic/colcon_ws/install/ros2_control_test_nodes', '/home/mauch/robot_folders/checkout/ur_ros2_galactic/colcon_ws/install/ros2_control_demo_hardware', '/home/mauch/robot_folders/checkout/ur_ros2_galactic/colcon_ws/install/diffbot_description', '/opt/ros/galactic']"

However, the error is most probably on the library

[fmauch]

With https://github.com/UniversalRobots/Universal_Robots_Client_Library/pull/131 this finally works.

However, I'll squash the two commits and change the commit message, as the script is not only used in headless mode.

@livanov93 would you like to make the changes or would you be fine with me doing them?

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Edit: Additionally, deleting the script from the driver is explicitly not part of this PR as this would effectively break setup for users. We can delete it once we branched out for humble, which we probably should do at any point soon.