[dr-autosync] switch to backup dc during sync_recover mode, flashback panic due to no leader for one region

## Bug Report

### What did you do?
Switch to backup dc during sync_recover mode, do online recovery, and flashback in the new backup cluster.

### What did you expect to see?

### What did you see instead?
[root@tiup-0 ~]# tiup ctl:v6.5.3 tikv --pd pd3-peer.e2e-dr-auto-sync-5r-func-tps-1744499-1-8:2379 flashback -v 442490139984003200
Starting component `ctl`: /root/.tiup/components/ctl/v6.5.3/ctl /root/.tiup/components/ctl/v6.5.3/ctl tikv --pd pd3-peer.e2e-dr-auto-sync-5r-func-tps-1744499-1-8:2379 flashback -v 442490139984003200
thread 'flashback' panicked at 'called `Result::unwrap()` on an `Err` value: Other("[components/pd_client/src/util.rs:878]: invalid store ID 0, not found")', cmd/tikv-ctl/src/main.rs:820:62
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: JoinError::Panic(Id(9), ...)', cmd/tikv-ctl/src/main.rs:945:6
Error: exit status 101

Above error cause by following region.

### What version of PD are you using (`pd-server -V`)?
sh-4.2# ./pd-server -V
Release Version: v6.5.3-hotfix0627
Edition: Community
Git Commit Hash: 22e04cea8095edbac23ff9354796070105e734be
Git Branch: heads/refs/tags/v6.5.3-hotfix0627
UTC Build Time: 2023-06-27 03:13:08

Seems it caused by cluster change to async after pd allocate id for region split and before region split started in tikv.
```
[2023/06/28 23:25:30.964 +08:00] [INFO] [cluster_worker.go:145] ["alloc ids for region split"] [region-id=3583] [peer-ids="[3584,3585,3586,3587,3588,3589,3590]"]
[2023/06/28 23:25:33.126 +08:00] [WARN] [stream.go:436] ["lost TCP streaming connection with remote peer"] [stream-reader-type="stream MsgApp v2"] [local-member-id=28e83f861b3ec367] [remote-peer-id=8e7df1128a41d7ab] [error="read tcp 10.200.57.142:59160->10.200.35.239:2380: i/o timeout"]
[2023/06/28 23:25:33.127 +08:00] [WARN] [peer_status.go:68] ["peer became inactive (message send to peer failed)"] [peer-id=8e7df1128a41d7ab] [error="failed to read 8e7df1128a41d7ab on stream MsgApp v2 (read tcp 10.200.57.142:59160->10.200.35.239:2380: i/o timeout)"]
[2023/06/28 23:25:33.235 +08:00] [WARN] [stream.go:436] ["lost TCP streaming connection with remote peer"] [stream-reader-type="stream Message"] [local-member-id=28e83f861b3ec367] [remote-peer-id=8e7df1128a41d7ab] [error="read tcp 10.200.57.142:59158->10.200.35.239:2380: i/o timeout"]
[2023/06/28 23:25:37.487 +08:00] [INFO] [audit.go:126] ["Audit Log"] [service-info="{ServiceLabel:SavePersistFile, Method:HTTP/1.1/POST:/pd/api/v1/admin/persist-file/DR_STATE, Component:anonymous, IP:10.200.57.142, StartTime:2023-06-28 23:25:37 +0800 CST, URLParam:{}, BodyParam:{\"state\":\"async_wait\",\"state_id\":3591,\"available_stores\":[2,9,10]}}"]

[2023/06/28 23:25:43.993 +08:00] [INFO] [audit.go:126] ["Audit Log"] [service-info="{ServiceLabel:SavePersistFile, Method:HTTP/1.1/POST:/pd/api/v1/admin/persist-file/DR_STATE, Component:anonymous, IP:10.200.57.142, StartTime:2023-06-28 23:25:43 +0800 CST, URLParam:{}, BodyParam:{\"state\":\"async\",\"state_id\":3592,\"available_stores\":[2,9,10]}}"]
```

```
[2023/06/28 23:25:47.645 +08:00] [INFO] [apply.rs:2470] ["split region"] [keys="key 7480000000000000FF535F728000000000FF09867E0000000000FA"] [region="id: 1223 start_key: 7480000000000000FF535F728000000000FF08A7580000000000FA end_key: 7480000000000000FF535F728000000000FF09FA3D0000000000FA region_epoch { conf_ver: 19 version: 69 } peers { id: 1224 store_id: 9 } peers { id: 1225 store_id: 11 } peers { id: 1226 store_id: 10 } peers { id: 1227 store_id: 8 role: Learner } peers { id: 1228 store_id: 2 } peers { id: 1229 store_id: 1 } peers { id: 3222 store_id: 1385 role: Learner }"] [peer_id=1224] [region_id=1223]
```