REGR: to_dict(orient={"records", "split", "dict"}) slowdown
- [x] closes #42352
- [x] tests added / passed
- [x] Ensure all linting tests pass, see [here](https://pandas.pydata.org/pandas-docs/dev/development/contributing.html#code-standards) for how to run them
- [x] whatsnew entry

Regression was due to each scalar value hitting `is_datetime_or_timedelta_dtype` -> `_is_dtype_type` where it falls most of the way through.
