REF: remove drop_level kwarg from MultiIndex._get_loc_level
- [ ] closes #xxxx
- [ ] tests added / passed
- [ ] Ensure all linting tests pass, see [here](https://pandas.pydata.org/pandas-docs/dev/development/contributing.html#code-standards) for how to run them
- [ ] whatsnew entry


yeah this is a pretty nasty piece of code ..... > yeah this is a pretty nasty piece of code .....

yah, lots of small steps to improve it coming up, after which there are some API design decisions we'll need to pin down e.g. #39775