Fixed tasks_queue and tasks_kill did not exist in zookeeper #1696 (#1734)

    private static final Logger logger = LoggerFactory.getLogger(TaskQueueZkImpl.class);

    private final ZookeeperOperator zookeeperOperator;

    @Autowired

    private ZookeeperOperator zookeeperOperator;

    public TaskQueueZkImpl(ZookeeperOperator zookeeperOperator) {

        this.zookeeperOperator = zookeeperOperator;

        try {

            String tasksQueuePath = getTasksPath(Constants.DOLPHINSCHEDULER_TASKS_QUEUE);

            String tasksCancelPath = getTasksPath(Constants.DOLPHINSCHEDULER_TASKS_KILL);

            for(String key : new String[]{tasksQueuePath,tasksCancelPath}){

                if(!zookeeperOperator.isExisted(key)){

                    zookeeperOperator.persist(key, "");

                    logger.info("create tasks queue parent node success : {}", key);

                }

            }

        } catch (Exception e) {

            logger.error("create tasks queue parent node failure", e);

        }

    }

    /**

     * get all tasks from tasks queue