[1.7.x] Renamed tests for util -> utils moves; refs #17627.

Backport of 8a9b0c15a6 from master

tests/admin_utils/tests.py

@@ -91,7 +91,7 @@ class NestedObjectsTests(TestCase):
         n.collect([Vehicle.objects.first()])
 
 
-class UtilTests(SimpleTestCase):
+class UtilsTests(SimpleTestCase):
     def test_values_from_lookup_field(self):
         """
         Regression test for #12654: lookup_field

tests/forms_tests/tests/test_utils.py

@@ -12,7 +12,7 @@ from django.utils.translation import ugettext_lazy
 from django.utils.encoding import python_2_unicode_compatible
 
 
-class FormsUtilTestCase(TestCase):
+class FormsUtilsTestCase(TestCase):
     # Tests for forms/utils.py module.
 
     def test_flatatt(self):