TST: Add test for operations on DataFrame with Interval CategoricalIndex
- [x] closes #27415
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

Yah these definitely don't belong in tests.indexing.  Is there anything DataFrame-specific about them, or could similar tests be written for Series etc?  If the latter, then these would go in tests.arithmetic.  If they are DataFrame-specific, then tests.frame.test_arithmetic thanks @yanglinlee 