[Bug]: AssignSegmentID still return success when it failed

[zhagnlu]

Is there an existing issue for this?

• [X] I have searched the existing issues

Environment

- Milvus version: master
- 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

when datacoord alloc segmentid failed, this interface return success instead of fail.

Expected Behavior

No response

Steps To Reproduce

No response

Milvus Log

No response

Anything else?

No response

[XuanYang-cn]

ut breaks

[XuanYang-cn]

@zhagnlu list of SegmentIDRequest represents different collection's segmentIDRequests, One Collection's failure shouldn't influence other collections.

As how proxy processing it,

we should append a SegmentAllocations with Non-success status

[congqixia]

It looks like the patch broke the design for proxy may assign segment id for multiple collections /cc @czs007

[XuanYang-cn]

/assign @zhagnlu /assign @czs007

[XuanYang-cn]

also we don't return err for RPC returns, but error status

[zhagnlu]

update it as return error status for every request, not return err all