Update python nodes SIGINT handling

[thomasmoore-torc]

Bug report

rclpy was updated to automatically handle SIGINT as part of this PR which was incorporated into the Humble release: ros2/rclpy#844

The python nodes in the demos repository were subsequently updated via the following PRs, but those changes were never incorporated into the examples repository.

• Update python nodes SIGINT handling demos#539
• Cleanups in demo_nodes_py. demos#555
• Exit with code 0 if ExternalShutdownException is raised demos#581

For consistency, and to ensure that an exception is not thrown when SIGINT is passed to the example python nodes, these same changes should be incorporated into this repository.

[fujitatomoya]

@thomasmoore-torc thanks for creating issue.

ros2/demos#539

i think #330 aligns with?

ros2/demos#555
ros2/demos#581

those seem like missing?

[thomasmoore-torc]

@fujitatomoya - it looks like #330 only updated the rclpy/executors examples but not any of the other rclpy examples (e.g. rclpy/topics/minimal_publisher/examples_rclpy_minimal_publisher/publisher_local_function.py).