[Bug]: fail to search after upgrade from 2.3.15 to 2.4.1 and roll back to 2.3.15

[yanliang567]

Is there an existing issue for this?

• I have searched the existing issues

Environment

- Milvus version: 2.3.15->2.4.1->2.3.15
- Deployment mode(standalone or cluster): standalone
- MQ type(rocksmq, pulsar or kafka):

Current Behavior

1. fail to search after rollback from 2.4.1 to 2.3.15
   pymilvus.exceptions.MilvusException: <MilvusException: (code=503, message=failed to query: node offline[node=2]: channel not available[channel=yanliang-2315-rootcoord-dml_1_449906074566018697v0])>
2. it looks like knowhere is not able to handle a higher index version(built with 2.4.1)
   

Expected Behavior

1. search successfully

Steps To Reproduce

1. deploy a milvus 2.3.15
2. insert 200k 768d vectors, build hnsw and load
3. verify search successfully
4. upgrade to milvus 2.4.1
5. insert 500k more vectors 
6. verify search successfully
7. rollback to 2.3.15

Milvus Log

pod names in 4am

yanliang-2315-etcd-0                                              1/1     Running       0               23h     10.104.30.50    4am-node38   <none>           <none>
yanliang-2315-milvus-standalone-57fcfd6498-s9p49                  1/1     Running       0               14h     10.104.4.65     4am-node11   <none>           <none>
yanliang-2315-minio-5fd98575b7-xxhmq                              1/1     Running       0               23h     10.104.20.18    4am-node22   <none>           <none>

Anything else?

No response

[yanliang567]

/assign @foxspy
/unassign