BUG: read_excel failed with empty rows after MultiIndex header
- [x] closes #40442
- [x] tests added / passed
- [x] Ensure all linting tests pass, see [here](https://pandas.pydata.org/pandas-docs/dev/development/contributing.html#code-standards) for how to run them
- [x] whatsnew entry

Prior to this fix, a blank data row after a MultiIndex header was a interpreted as containing a blank index name, but that only works if the user has specified an index column. If index_col is None all subsequent rows should be treated as data, even if the first one is empty.
@dsaxton thanks for catching those @jreback I've added the new comments; let me know if anything else is needed. Thanks thanks @ahawryluk very nice