Isolated sitemaps test from ABSOLUTE_URL_OVERRIDES

Refs #15988.

django/contrib/sitemaps/tests/generic.py

@@ -1,7 +1,9 @@
 from django.contrib.auth.models import User
+from django.test.utils import override_settings
 
 from .base import SitemapTestsBase
 
+@override_settings(ABSOLUTE_URL_OVERRIDES={})
 class GenericViewsSitemapTests(SitemapTestsBase):
 
     def test_generic_sitemap(self):