`pd-ctl member leader resign` does not consider `leader_priority`

## Bug Report

### What did you do?

```
pd0 leader_priority=1 | Leader
pd1 leader_priority=1
pd2 leader_priority=0
```

run `pd-ctl member leader resign`

### What did you expect to see?

Transfer leader from pd0 to pd1.

### What did you see instead?

pd2 may temporarily become the Leader.

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

v5.3.0