100T global sort import from gcs failed with fail to split region

## Bug Report

Please answer these questions before submitting your issue. Thanks!

### 1. Minimal reproduce step (Required)
```sql
[11:45:18]TiDB root:(none)> show import jobs\G
***************************[ 1. row ]***************************
Job_ID | 1
Data_Source | gs://xxx
Target_Table | `test`.`t`
Table_ID | 104
Phase | importing
Status | failed
Source_File_Size | 121.4TiB
Imported_Rows |
Result_Message | [BR:Restore:ErrRestoreSplitFailed]fail to split region
Create_Time | 2024-01-17 15:15:48.805618
Start_Time | 2024-01-17 15:15:50.740458
End_Time | 2024-01-18 03:36:42.961893
Created_By | root@%
1 row in set
Time: 0.287s
```

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

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

### 4. What is your TiDB version? (Required)
```sql
[11:49:53]TiDB root:(none)> select type,version,git_hash from information_schema.cluster_info group by type;
+------+-------------+------------------------------------------+
| type | version | git_hash |
+------+-------------+------------------------------------------+
| tikv | 8.0.0-alpha | 7b50d052bc7cce218ca03a0f1f45c63634195fdd |
| pd | 8.0.0-alpha | 3a12148b573944890c6ecc8e270f458a8369bb74 |
| tidb | 7.6.0-test | abd62b804fd802a5f42448ef422ab5f2c4b01900 |
+------+-------------+------------------------------------------+
```