global sort read wrong offset when read stat file of onefile writer

[ywqzzy]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

run 1T import into with global sort

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

import success.

3. What did you see instead (Required)

[2023/12/18 11:50:21.137 +00:00] [Info] [reader.go:42] [arguments] [data-file-count=34] [stat-file-count=34] [start-key="dIAAAAAAAABwX2mAAAAAAAAACgQAAAAH/eTrQwExMDYwNTY2N/8xRk14N2ZPTf80QlhlZlNiNP81Skh4bmYzZf9iYmhaUkJQQ/9xAAAAAAAAAPg="] [end-key="dIAAAAAAAABwX2mAAAAAAAAACgQAAAAH/eTraQExODI5MjQ0MP83SG9yY3RQU/9hNFptRjhSTP84RUF3dE1sUP9Ia3UweFN2bf8wAAAAAAAAAPg="]

[2023/12/18 11:50:21.866 +00:00] [Info] [engine.go:197] ["found hotspot file in getFilesReadConcurrency"] [filename=240002/360025/36e833b5-093a-412f-b8d8-12405020fed2_stat/one-file] [startOffset=643824000] [endOffset=0] ["expected concurrency"=4398046510950]

4. What is your TiDB version? (Required)

master