[BUG]: Fix regression in read_table with delim_whitespace=True
- [x] closes #35958
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

We could write a private function which is called from read_csv and read_table with the appropriate default_set alternatively.

Edit: Black_pandas formats files not touched by myself. Was there an update or change of guidelines?