fix: physics callback leaks when rebuilding scenario

[andrewwhitecdw]

This PR addresses the following issue in exts/omni.ext.mobility_gen/omni/ext/mobility_gen/extension.py: physics callback leaks when rebuilding scenario.

Changes

• exts/omni.ext.mobility_gen/omni/ext/mobility_gen/extension.py: physics callback leaks when rebuilding scenario.

Details

Before:

    def clear_scenario(self):
        self.scenario = None
        self.cached_stage_path = None

After:

    def clear_scenario(self):
        world = get_world()
        if world is not None:
            try:
                world.remove_physics_callback("scenario_physics")
            except Exception:
                pass
        self.scenario = None
        self.cached_stage_path = None