BUG: Fix empty MultiIndex DataFrame xlsx export
Fix Excel xlsx export of empty (zero rows) DataFrame with MultiIndex on both axes.

- [x] closes #57696
- [x] [Tests added and passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#writing-tests) if fixing a bug or adding a new feature
- [x] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).
- [x] Added [type annotations](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#type-hints) to new arguments/methods/functions.
- [x] Added an entry in the latest `doc/source/whatsnew/vX.X.X.rst` file if fixing a bug or adding a new feature.

Thanks @speleo3 - nice fix! Thanks a lot for fixing this. I'm running into this exact issue at work. Since 3.0.0 hasn't been released yet, is there a workaround in the meantime? My attempt:

```py
if df.empty and not df.columns:
    df.columns = []
```