BUG: Index.drop raising Error when Index has duplicates
- [x] closes #38051
- [x] closes #33494
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

@jbrockmendel  This should deal with duplicates. For MultiIndex sometimes a slice with stepzize greater than zero was given, which dropped to many elements
Exited for the MultiIndex cases, because would have to catch a PerformanceWarning there if it is not sorted and we are testing this at another place too. looks good, @phofl can you merge master and ping on green. Thanks for merging. Found that warnings call in another Test. Will look through as a follow up and clean this up @phofl test_drop_with_duplicates_in_index failing on 32bit (not all tests completed on other envs yet) Dtype casting issue, will look into this later. I think this is a configuration which can not work on 32 bit for this one test, so I skipped it @jreback green thanks @phofl 