Function read_parquet_position_deletes_from_file 

pub async fn read_parquet_position_deletes_from_file(
    file_io: &FileIO,
    delete_file: &DataFile,
) -> Result<DeleteVector>

Reads the positions stored in a V2 Parquet position-delete file into a [DeleteVector].

The file’s schema is (file_path, pos). Callers only invoke this after the entry’s referenced_data_file already matched the target data file, and the files we write are file-scoped (every row shares one file_path), so the file_path column is redundant here: we project only the pos column and read every value.