CLN: (re-)enable infer_dtype to catch complex
- [x] takes a small bite out of #23554
- [x] tests added / passed
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`

`complex` should already be inferred according to the docstring, but isn't. I'm hitting this while working on my PR for #23833 so splitting that off as a separate change.
