Remove bogus pagination test from sites index

The sites index is not paginated, and never has been. All this test is doing is confirming that we can pass some random unrecognised URL parameter to the page and it will have no effect. :-)

wagtail/sites/tests.py

@@ -20,12 +20,6 @@ class TestSiteIndexView(WagtailTestUtils, TestCase):
         self.assertEqual(response.status_code, 200)
         self.assertTemplateUsed(response, "wagtailadmin/generic/index.html")
 
-    def test_pagination(self):
-        pages = ["0", "1", "-1", "9999", "Not a page"]
-        for page in pages:
-            response = self.get({"p": page})
-            self.assertEqual(response.status_code, 200)
-
 
 class TestSiteCreateView(WagtailTestUtils, TestCase):
     def setUp(self):