Lightning encountered error PD server timeout and remote checksum failed

## Bug Report

Please answer these questions before submitting your issue. Thanks!

### 1. Minimal reproduce step (Required)
1. deploy tidb cluster of version 8.5.0
2. import data from s3/minio by nightly version lightning

### 2. What did you expect to see? (Required)

resotre data successfully.

### 3. What did you see instead (Required)

encountered error after remote checksum.

```
[2025/06/18 16:17:33.961 +08:00] [INFO] [import.go:1456] ["restore table completed"] [table=`test`.`usertable`] [takeTime=25m9.52879663s] []
[2025/06/18 16:17:33.961 +08:00] [INFO] [import.go:1153] ["cancel periodic actions"] [do=true]
[2025/06/18 16:17:33.961 +08:00] [INFO] [tikv_mode.go:61] ["switch tikv mode"] [mode=Normal]
[2025/06/18 16:17:34.027 +08:00] [INFO] [table_import.go:1034] ["local checksum"] [table=`test`.`usertable`] [checksum="{cksum=15457348682385349679,size=420176047757,kvs=200000000}"]
[2025/06/18 16:17:34.027 +08:00] [INFO] [checksum_helper.go:73] ["remote checksum start"] [table=usertable]
[2025/06/18 16:18:38.139 +08:00] [WARN] [checksum.go:326] ["remote checksum failed"] [db=test] [table=usertable] [error="[tikv:9001]PD server timeout: start timestamp may fall behind safe point; [tikv:9001]PD server timeout: start timestamp may fall behind safe point; [tikv:9001]PD server timeout: start timestamp may fall behind safe point; [tikv:9001]PD server timeout: start timestamp may fall behind safe point; [tikv:9001]PD server timeout: start timestamp may fall behind safe point; [tikv:9001]PD server timeout: start timestamp may fall behind safe point; [tikv:9001]PD server timeout: start timestamp may fall behind safe point; [tikv:9001]PD server timeout: start timestamp may fall behind safe point"]
```
### 4. What is your TiDB version? (Required)

tidb v8.5.0
lightning nightly