Do not use event handler for loading composable nodes

Fixes #114.

Due to the asynchronous nature of the LoadComposableNodes action, an event handler causes the launch configuration is popped if ComposableNodeContainer appears inside a group or include action.
It seems to me we can simply return the load node action, which will get executed after the ComposableNodeContainer action. The use of an event handler is vestigial of a refactoring done in #16, and doesn't appear to be necessary.

Signed-off-by: Jacob Perron <[email protected]>

Author: jacobperron

launch_ros/launch_ros/actions/composable_node_container.py

@@ -92,17 +92,17 @@ def execute(self, context: LaunchContext) -> Optional[List[Action]]:
             from .load_composable_nodes import LoadComposableNodes
             # Perform load action once the container has started.
             load_actions = [
-                RegisterEventHandler(
-                    event_handler=OnProcessStart(
-                        target_action=self,
-                        on_start=[
+                # RegisterEventHandler(
+                #     event_handler=OnProcessStart(
+                #         target_action=self,
+                #         on_start=[
                             LoadComposableNodes(
                                 composable_node_descriptions=self.__composable_node_descriptions,
                                 target_container=self
                             )
-                        ]
-                    )
-                )
+                #         ]
+                #     )
+                # )
             ]
         container_actions = super().execute(context)  # type: Optional[List[Action]]
         if container_actions is not None and load_actions is not None: