执行gremlin语句的job任务报错- 语句为"graph.truncateBackend()"

### Expected behavior 期望表现
由于使用cassandra后端进行truncateBackend操作耗时较长，期望能通过gremlin job方式实现

### Actual behavior 实际表现

### Steps to reproduce the problem 复现步骤
1. 通过gremlin job 接口 或者 hubble 执行 graph.truncateBackend()操作
2.查看执行结果以及日志

Start by reproducing graph.truncateBackend() through the Gremlin job interface or Hubble, then inspect the execution result and logs shown in the issue. The fix is complete when the Cassandra-backed operation runs successfully as a job and reports a successful result without the observed error.

Written by the indexing model from the issue text.