Kafka brokers need to finish the shutdown process before the zookeepers do.
So start the zookeepers, then the kafka brokers will retry the shutdown process.
先关闭Kafka,等关闭完之后再关闭Zookeeper，否则，Kafka brokers无法关闭
参考：https://stackoverflow.com/questions/25568178/kafka-server-stop-sh-not-working-when-kafka-started-from-python-script
