after hot replace tls ca and cert ,pd/tikv error

## Bug Report

### What did you do?
1. deploy tiup cluster with tls
2. generate self issued ca and use ca issue tidb/tikv/pd cert
3. hot replace ca and cert

### What did you expect to see?
1. pd/tikv work well
### What did you see instead?
1. pd down tikv n/a

2. pd error log
3. tikv error log
4. if stop cluster and replace ca and cert, all ok

### What version of PD are you using (`pd-server -V`)?