Delete all group outputs.

def experiment_group_pre_delete(sender, **kwargs):
    """Delete all group outputs."""
    instance = kwargs['instance']

    if instance.is_selection:
        return

    # Delete outputs and logs
    celery_app.send_task(
        SchedulerCeleryTasks.STORES_SCHEDULE_OUTPUTS_DELETION,
        kwargs={
            'persistence': instance.persistence_outputs,
            'subpath': instance.subpath,
        },
        countdown=conf.get('GLOBAL_COUNTDOWN'))
    celery_app.send_task(
        SchedulerCeleryTasks.STORES_SCHEDULE_LOGS_DELETION,
        kwargs={
            'persistence': instance.persistence_logs,
            'subpath': instance.subpath,
        },
        countdown=conf.get('GLOBAL_COUNTDOWN'))