cfanschina

[Bug] 使用count(distinct(某列)) 进行分组统计时，统计出来数据为0

2

### Search before asking - [x] I searched in the [issues](https://github.com/apache/iotdb/issues) and found nothing similar. ### Version 从v0.13到v2都测试了一遍，都一样的问题 ### Describe the bug and provide the minimal reproduce step 如图，不加group by...