[Flaky test] `openedx/core/djangoapps/user_authn/views/tests/test_logistration.py::LoginAndRegistrationTest::test_login_and_registration_form_ratelimited`

This test fails intermittently and has been deleted according to the Flaky Test Process in https://github.com/openedx/edx-platform/pull/32459.

See docs on how to address flaky tests for why this should be fixed and how to go about it.

Failure output:

=================================== FAILURES ===================================
____ LoginAndRegistrationTest.test_login_and_registration_form_ratelimited _____

self = <openedx.core.djangoapps.user_authn.views.tests.test_logistration.LoginAndRegistrationTest testMethod=test_login_and_registration_form_ratelimited>

    def test_login_and_registration_form_ratelimited(self):
        """
        Test that rate limiting for logistration enpoints works as expected.
        """
        login_url = reverse('signin_user')
        for _ in range(5):
            response = self.client.get(login_url)
            assert response.status_code == 200
    
        # then the rate limiter should kick in and give a HttpForbidden response
        response = self.client.get(login_url)
>       assert response.status_code == 429
E       assert 200 == 429
E        +  where 200 = <HttpResponse status_code=200, "text/html; charset=utf-8">.status_code

openedx/core/djangoapps/user_authn/views/tests/test_logistration.py:132: AssertionError

(Previously filed as https://2u-internal.atlassian.net/browse/CR-5847.)

Notes copied from deletion PR:

• [idea] It is unclear whether it would pass if it were tried one more time, or given a little more sleep, but maybe the test could be written so if the 429 isn't seen when expected, it does a very small sleep and tries one last time. Or, maybe there is a real bug in the rate limiting code and real failures to rate limit might occur at times?
  • If you choose the workaround in place of looking to see if there is a real flaky bug, then you should comment next to the workaround that if it ever fails, we should really look into whether this is a bug that is not self-healing with our security code.
• [idea] Rerunning the test many times in a tight loop locally may help duplicate?

Start with openedx/core/djangoapps/user_authn/views/tests/test_logistration.py and the Flaky Test Process linked in the issue. Run the named test repeatedly and review the recorded 200-versus-429 failure, then determine whether the test or rate-limiting behavior needs correction. Done means the rate-limit behavior is reliably verified without intermittent failure.