Remove tf_prefix from ur_control.launch.py (#1020)

This is now part of ur_rsp.launch.py

Author: Felix Exner (fexner)

ur_robot_driver/launch/ur_control.launch.py

@@ -280,15 +280,6 @@ def generate_launch_description():
             "publishes the description topic.",
         )
     )
-    declared_arguments.append(
-        DeclareLaunchArgument(
-            "tf_prefix",
-            default_value="",
-            description="tf_prefix of the joint names, useful for "
-            "multi-robot setup. If changed, also joint names in the controllers' configuration "
-            "have to be updated.",
-        )
-    )
     declared_arguments.append(
         DeclareLaunchArgument(
             "use_mock_hardware",