[Bug]: the log level doesn't take effect when changing it at runtime

[SimFG]

Is there an existing issue for this?

• [X] I have searched the existing issues

Environment

- Milvus version:
- Deployment mode(standalone or cluster):
- MQ type(rocksmq, pulsar or kafka):    
- SDK version(e.g. pymilvus v2.0.0rc2):
- OS(Ubuntu or CentOS): 
- CPU/Memory: 
- GPU: 
- Others:

Current Behavior

the log level doesn't take effect when changing it at runtime

Expected Behavior

No response

Steps To Reproduce

No response

Milvus Log

No response

Anything else?

No response

[SimFG]

/assign @SimFG