Fixed #34305 -- Changed GeoIP2 tests to use MaxMind test databases.

GEOIP_SETTINGS is removed from the global scope as this prevents
modifications to the settings using @override_settings in tests.

Additional improvements now that we have stable test databases include:

- Made testing more comprehensive and improved coverage
- Patched socket.gethostbyname() for whole test case
- Added testing of non-free GeoIP2 databases

Co-authored-by: Tom Forbes <tom@tomforb.es>

tests/gis_tests/data/geoip2/LICENSE

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+This work is licensed under the Creative Commons Attribution-ShareAlike 3.0
+Unported License. To view a copy of this license, visit
+http://creativecommons.org/licenses/by-sa/3.0/ or send a letter to Creative
+Commons, 444 Castro Street, Suite 900, Mountain View, California, 94041, USA.

tests/gis_tests/data/geoip2/README

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+These test databases are taken from the following repository:
+
+https://github.com/maxmind/MaxMind-DB/