Reduce the experiments to restart.

def get_reduced_configs(self):
        """Reduce the experiments to restart."""
        iteration_config = self.experiment_group.iteration_config
        if iteration_config is None:
            logger.error(
                'Experiment group `%s` attempt to update iteration, but has no iteration',
                self.experiment_group.id,
                extra={'stack': True})
            return
        search_manager = self.experiment_group.search_manager

        # Get the number of experiments to keep
        n_configs_to_keep = search_manager.get_n_config_to_keep_for_iteration(
            iteration=iteration_config.iteration,
            bracket_iteration=iteration_config.bracket_iteration)

        # Get the last group's experiments metrics
        experiments_metrics = self.experiment_group.iteration_config.experiments_metrics
        if experiments_metrics is None:
            raise ExperimentGroupException()

        # Order the experiments
        reverse = Optimization.maximize(
            self.experiment_group.hptuning_config.hyperband.metric.optimization)
        experiments_metrics = sorted(experiments_metrics, key=lambda x: x[1], reverse=reverse)

        # Keep n experiments
        return [xp[0] for xp in experiments_metrics[:n_configs_to_keep]]