Update  Lucene104PostingsWriter level1skipdata doc count

### Description

Since `LEVEL1_FACTOR = 32 & BLOCK_SIZE=256`, so the truly docs here should be **8192**

<img width="1077" height="109" alt="Image" src="https://github.com/user-attachments/assets/1f1bf048-aaba-4825-b680-bc0cf86767a8" />