MAINT: Use float arange when required or intended
Ensure arange is float when intened or required by NumPy

- [X] passes `black pandas`
- [X] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [X] whatsnew entry

Use float initialization to allow NaN to be set of when setting floating points later.  Used to be part of #35427, but split it out to have one PR one issue.  Required by Future NumPy. Fixes about 12 of the np-dev fails. Thanks @bashtage  @MeeseeksDev backport to 1.1.x