Drop redundant TestLocale
We have the `TestLocaleUtils` class in `tests/util/test_util.py`
https://github.com/pandas-dev/pandas/blob/master/pandas/tests/util/test_util.py#L421
which is more comprehensive and includes `test_get_locales` which is functionally identical.

- [ ] closes #xxxx
- [ ] tests added / passed
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry
