CI: Revert splitting 3.10 tests
Maths says this should work now.

- [ ] closes #44173
- [ ] tests added / passed
- [ ] Ensure all linting tests pass, see [here](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit) for how to run them
- [ ] whatsnew entry

Don't backport.
hmm something taking a long time > hmm something taking a long time

Not the Python 3.10 tests, though. Just the usual suspects :) gentle ping @jreback. This is ready. can u rebase once more thanks @lithomas1 