when pd `relication.max-replicas` is 1, tikv will get stuck when graceful restart

[AkiraXie]

Bug Report

What version of TiDB Operator are you using?

1.3.8 What storage classes exist in the Kubernetes cluster and what are used for PD/TiKV pods?

What's the status of the TiDB cluster pods?

What did you do?

1. cluster has 1 pd and 4 tikv
2. pd set config relication.max-replicas =1
3. tikv graceful restarted https://docs.pingcap.com/zh/tidb-in-kubernetes/stable/restart-a-tidb-cluster#%E4%BC%98%E9%9B%85%E6%BB%9A%E5%8A%A8%E9%87%8D%E5%90%AF-tidb-%E9%9B%86%E7%BE%A4%E7%BB%84%E4%BB%B6%E7%9A%84%E6%89%80%E6%9C%89-pod

What did you expect to see? tikv will restart successfully What did you see instead? tikv get stuck

[mikechengwei]

/assign