TST: adds test for Series and argwhere interaction
- [x] closes #35331 
- [x] [Tests added and passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#writing-tests) if fixing a bug or adding a new feature
- [x] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).
- [ ] ~Added [type annotations](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#type-hints) to new arguments/methods/functions.~ N/A
- [ ] ~Added an entry in the latest `doc/source/whatsnew/vX.X.X.rst` file if fixing a bug or adding a new feature.~ N/A

### Details:
- Adds missing tests mentioned by @mroeschke last week. 
- Dug around briefly in other issues / prs to link the fix to this bug however nothing jumped out. 
Thanks @mcgeestocks 