[Bug]: sharding test: the number of replica is incorrect.

### Is there an existing issue for the same bug?

- [X] I have checked the existing issues.

### Branch Name

main

### Commit ID

55d94f196

### Other Environment Information

```Markdown
- Hardware parameters:
- OS type:
- Others:
```

### Actual Behavior

**5个分区，5个cn，应该5个shard，每个cn上有1个shard，现在shard一共有12个，且分布不均匀**

**shard监控**：https://grafana.ci.matrixorigin.cn/d/ea89d958-08d2-440b-bf17-fa9c6e56f3c6/sharding-metrics?orgId=1&var-interval=1m&var-namespace=mo-shardingtest&var-pod=All&from=1727596200000&to=1727596560000

### Expected Behavior

_No response_

### Steps to Reproduce

```Markdown
启动1cn，使用mo-load工具测试update 100并发

启动5cn，使用5个mo-load工具连到不同的cn上同时测试update 100并发

具体我更新在文档中私发
```

### Additional information

_No response_