fix Rolling for multi-index and reversed index.
Fix Rolling operation for level of multi-index and descending time index (that is monotonic, but decreasing).

- [x] closes #19248
- [x] closes #15584
- [x] tests passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry
