TestResignTSOPrimaryForward is flaky

## Flaky Test

### Which jobs are failing

```
server_test.go:234:
Error Trace: /home/runner/work/pd/pd/tests/integrations/mcs/tso/server_test.go:234
/home/runner/work/pd/pd/tests/integrations/mcs/tso/server_test.go:323
Error: Received unexpected error:
[PD:etcd:ErrStartEtcd]listen tcp 127.0.0.1:39627: bind: address already in use: listen tcp 127.0.0.1:39627: bind: address already in use
github.com/pingcap/errors.AddStack
/home/runner/go/pkg/mod/github.com/pingcap/errors@v0.11.5-0.20211224045212-9687c2b0f87c/errors.go:174
github.com/pingcap/errors.(*Error).GenWithStackByCause
/home/runner/go/pkg/mod/github.com/pingcap/errors@v0.11.5-0.20211224045212-9687c2b0f87c/normalize.go:307
github.com/tikv/pd/server.(*Server).startEtcd
/home/runner/work/pd/pd/server/server.go:329
github.com/tikv/pd/server.(*Server).Run
/home/runner/work/pd/pd/server/server.go:618
github.com/tikv/pd/tests.(*TestServer).Run
/home/runner/work/pd/pd/tests/cluster.go:127
github.com/tikv/pd/tests.RunServer.func1
/home/runner/work/pd/pd/tests/cluster.go:577
runtime.goexit
/opt/hostedtoolcache/go/1.23.2/x64/src/runtime/asm_amd64.s:1700
github.com/tikv/pd/tests.RunServers
/home/runner/work/pd/pd/tests/cluster.go:589
github.com/tikv/pd/tests.(*TestCluster).RunInitialServers
/home/runner/work/pd/pd/tests/cluster.go:601
github.com/tikv/pd/tests/integrations/mcs/tso.NewAPIServerForward
/home/runner/work/pd/pd/tests/integrations/mcs/tso/server_test.go:233
github.com/tikv/pd/tests/integrations/mcs/tso.TestResignTSOPrimaryForward
/home/runner/work/pd/pd/tests/integrations/mcs/tso/server_test.go:323
testing.tRunner
/opt/hostedtoolcache/go/1.23.2/x64/src/testing/testing.go:[169](https://github.com/tikv/pd/actions/runs/11454903722/job/31869908930?pr=8732#step:4:170)0
runtime.goexit
/opt/hostedtoolcache/go/1.23.2/x64/src/runtime/asm_amd64.s:[170](https://github.com/tikv/pd/actions/runs/11454903722/job/31869908930?pr=8732#step:4:171)0
Test: TestResignTSOPrimaryForward
--- FAIL: TestResignTSOPrimaryForward (0.15s)
```

### CI link

https://github.com/tikv/pd/actions/runs/11454903722/job/31869908930?pr=8732

### Reason for failure (if possible)

### Anything else