using v6.5.1 lightning import data to master fail

## Bug Report

Please answer these questions before submitting your issue. Thanks!

### 1. Minimal reproduce step (Required)

tidb cluster upgrade from 6.0.0 to 6.5.1-pre
import data to 6.0.0 cluster using 6.5.1 lightning

### 2. What did you expect to see? (Required)
import success
### 3. What did you see instead (Required)
import fail
print many warning:
{"level":"warn","ts":"2023-03-07T03:08:03.956Z","logger":"etcd-client","caller":"v3@v3.5.2/retry_interceptor.go:62","msg":"retrying of unary invoker failed","target":"etcd-endpoints://0xc000c22380/src-tidb-pd.fb-testbed-comp-2nrpj:2379","attempt":0,"error":"rpc error: code = DeadlineExceeded desc = latest balancer error: last connection error: connection error: desc = \"transport: Error while dialing dial tcp 10.244.7.55:2379: connect: connection refused\""}

### 4. What is your TiDB version? (Required)
v6.5.1-pre