can't select CLUSTER_INFO table when TLS between server components is enabled

[LinuxGit]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. What did you do?
   If possible, provide a recipe for reproducing the error.
   enableTLSCluster, See https://github.com/pingcap/tidb-operator/blob/master/charts/tidb-cluster/values.yaml#L61.

2. What did you expect to see?
   select INFORMATION_SCHEMA.CLUSTER_INFO table

3. What did you see instead?

 [INFORMATION_SCHEMA]> select * from CLUSTER_INFO;
ERROR 1105 (HY000): Get http://db-pd:2379/pd/api/v1/config/cluster-version: EOF

4. What version of TiDB are you using (tidb-server -V or run select tidb_version(); on TiDB)?
   v4.0.0-beta.1

[jackysp]

PTAL @lysu