REF: fewer simple_new calls in DTA._generate_range GH#24562
- [x] closes #24562
- [ ] tests added / passed
- [x] 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

The _simple_new calls are cheaper than they were back then, so we won't see that much improvement.  Still should be better than nothing.

great