CLN: Revert "Return Python integers" (not needed after #20989)
This reverts commit 8e3d4d08501dc83d4c2302686c8342e7448c78e5.

- [x] tests passed
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`

I had introduced the explicit casting to solve broken tests on Windows, but @jreback's #20989 is the correct way to do it, so these are now redundant.

looks ok, but oddly failing on 2.7 / windows > looks ok, but oddly failing on 2.7 / windows

Uhm, OK: I thought it was irrelevant, but given that it's not, and I have no idea why... never mind. (I'm failing to understand how the dtype of ``np.where``... changes with the platform.