Broken launch files for Galactic (on Ubuntu Focal)

[jrbaxter0]

Please complete the following information:

• OS and Version: Ubuntu 20.04
• ROS Version: Galactic
• Downloaded from Official Repository
• Version: 2.2.0-1focal.20220430.170126

Describe the bug The current binaries for galactic (on Ubuntu Focal) have broken launch files. It seems #435 resolves this, but it doesn't seem to have been applied to the current binaries. Perhaps it needs to be patched to a different branch or a new release with the changes pushed?

To Reproduce Steps to reproduce the behavior:

1. Install binaries: sudo apt install ros-galactic-velodyne
2. Use included launch files: ros2 launch velodyne velodyne-all-nodes-VLP32C-launch.py
3. The launch process crashes, see error:

   
   Task exception was never retrieved
   future: <Task finished name='Task-2' coro=<LaunchService._process_one_event() done, defined at /opt/ros/galactic/lib/python3.8/site-packages/launch/launch_service.py:226> exception=InvalidLaunchFileError('py')>
   Traceback (most recent call last):
   File "/opt/ros/galactic/lib/python3.8/site-packages/launch/launch_description_sources/any_launch_file_utilities.py", line 53, in get_launch_description_from_any_launch_file
   return loader(launch_file_path)
   File "/opt/ros/galactic/lib/python3.8/site-packages/launch/launch_description_sources/python_launch_file_utilities.py", line 68, in get_launch_description_from_python_launch_file
   return getattr(launch_file_module, 'generate_launch_description')()
   File "/opt/ros/galactic/share/velodyne/launch/velodyne-all-nodes-VLP32C-launch.py", line 45, in generate_launch_description
   velodyne_driver_node = launch_ros.actions.Node(package='velodyne_driver',
   TypeError: __init__() missing 1 required keyword-only argument: 'executable'

The above exception was the direct cause of the following exception:

Traceback (most recent call last): File "/opt/ros/galactic/lib/python3.8/site-packages/launch/launch_service.py", line 228, in _process_one_event await self.process_event(next_event) File "/opt/ros/galactic/lib/python3.8/site-packages/launch/launch_service.py", line 248, in process_event visit_all_entities_and_collect_futures(entity, self.context)) File "/opt/ros/galactic/lib/python3.8/site-packages/launch/utilities/visit_all_entities_and_collect_futures_impl.py", line 45, in visit_all_entities_and_collect_futures futures_to_return += visit_all_entities_and_collect_futures(sub_entity, context) File "/opt/ros/galactic/lib/python3.8/site-packages/launch/utilities/visit_all_entities_and_collect_futures_impl.py", line 45, in visit_all_entities_and_collect_futures futures_to_return += visit_all_entities_and_collect_futures(sub_entity, context) File "/opt/ros/galactic/lib/python3.8/site-packages/launch/utilities/visit_all_entities_and_collect_futures_impl.py", line 38, in visit_all_entities_and_collect_futures sub_entities = entity.visit(context) File "/opt/ros/galactic/lib/python3.8/site-packages/launch/action.py", line 108, in visit return self.execute(context) File "/opt/ros/galactic/lib/python3.8/site-packages/launch/actions/include_launch_description.py", line 130, in execute launch_description = self.launch_description_source.get_launch_description(context) File "/opt/ros/galactic/lib/python3.8/site-packages/launch/launch_description_source.py", line 84, in get_launch_description self._get_launch_description(self.expanded_location) File "/opt/ros/galactic/lib/python3.8/site-packages/launch/launch_description_sources/any_launch_description_source.py", line 53, in _get_launch_description return get_launch_description_from_any_launch_file(location) File "/opt/ros/galactic/lib/python3.8/site-packages/launch/launch_description_sources/any_launch_file_utilities.py", line 56, in get_launch_description_from_any_launch_file raise InvalidLaunchFileError(extension, likely_errors=exceptions) launch.invalid_launch_file_error.InvalidLaunchFileError: Caught exception when trying to load file of format [py]: init__() missing 1 required keyword-only argument: 'executable'

**Expected behavior**
The launch file would start up some nodes, and I would see it complain about not being connected to a Velodyne sensor.

[JWhitleyWork]

The change can be applied to the galactic-devel branch but galactic is, unfortunately, EOL so my PR to release a new version would be rejected. Sorry about this. Please create a PR if you would like it applied to the source branch.