BUG: GH12824 fixed apply() returns different result depending on whet…
- [x] closes #12824 
- [x] tests added / passed
- [x] passes `git diff upstream/master | flake8 --diff`
- [x] whatsnew entry

In `_wrap_applied_output` for `NDFrameGroupBy`, if the first result of `apply` is `None`, find the first non-`None` result to determine behavior
