Update cities.py and counties.py to Use USGS GNIS Data

# 💡 Summary #

Use city and county data from [USGS](https://www.usgs.gov/us-board-on-geographic-names/download-gnis-data) instead of Wikipedia.
See [CyHy example here](https://github.com/cisagov/cyhy-core/blob/develop/var/load_places.sh).

## Motivation and context ##
USGS is an official source for this data.
See https://github.com/cisagov/XFD/pull/82#discussion_r1529095617

Start by reading cities.py and counties.py, then compare their current Wikipedia data handling with the CyHy example in var/load_places.sh. Review the USGS GNIS download format and determine how it maps to the existing city and county data. Done means both files use USGS data instead of Wikipedia while preserving the expected outputs.

Written by the indexing model from the issue text.