fix: parquet hybrid RLE encoding did not always align to bit width

[nameexhaustion]

Fixes #13818.

If there were remainder values after dividing by the block size, these remainder values were not written with alignment to the bit width.

This crashes spark because spark reads bitWidth values at a time:

            // values are bit packed 8 at a time, so reading bitWidth will always work
            ByteBuffer buffer = in.slice(bitWidth);

(source https://github.com/apache/spark/blob/ce5ddad990373636e94071e7cef2f31021add07b/sql/core/src/main/java/org/apache/spark/sql/execution/datasources/parquet/VectorizedRleValuesReader.java#L934-L935)

Note to reproduce the issue on main, one should use an Int32 column of values instead of String, and ensure that the output of pq.read_metadata().row_group(0).column(0) contains RLE_DICTIONARY under encodings. This df should reproduce the issue:

pl.Series(
    "test_data",
    20 * [1, 2, 3],
    dtype=pl.Int32,
).to_frame()

Relevant spec page https://parquet.apache.org/docs/file-format/data-pages/encodings/

[ritchie46]

Can you add a comment to this PR here?

[ritchie46]

Thanks a lot for the fix! I left one minor comment.