Test: Tests break when pycountries updates its list of countries

[feanil]

Everytime pycountries updates the list of countries, edx-platform tests fail because we have a copy of the list from that library as a set of test constants: https://github.com/openedx/edx-platform/blob/master/openedx/core/djangoapps/user_api/tests/test_constants.py

This is super brittle and it's unclear what value it's providing. Do we need these tests? What are they doing? Can we test what we care about in a less brittle way?

Investigate the tests that use the SORTED_COUNTRIES constant and where it's used and see if we can get rid of it.

[Ritikkhulbe]

Opened #39045 to replace the manually maintained country snapshot with the live django-countries data used by the application. This keeps the existing registration option/default assertions while preventing dependency country-list updates from breaking the tests.