[Bug]: empty Array result set does not set ElementType

[congqixia]

Is there an existing issue for this?

• I have searched the existing issues

Environment

- Milvus version: 7d7d67d
- Deployment mode(standalone or cluster): both
- 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 empty search/query result set field data does not set ElementType field for array data

Expected Behavior

ElementType shall always be set for Array datatype

Steps To Reproduce

No response

Milvus Log

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Anything else?

No response