When using ClickHouse as the data source and configuring the alarm rules, the error "Error executing query: err:cluster not exists" will occur

### Question and Steps to reproduce

夜莺v8.0.0版本
添加告警规则，输入查询条件，点击数据预览即可复现

<img width="1166" height="591" alt="Image" src="https://github.com/user-attachments/assets/03ac51b9-a93e-4910-9fb2-544fa7e247ca" />


### Relevant logs and configurations

```text
无
```

### Version

夜莺v8.0.0版本