use support.rmtree instead of shutil (closes #19614)

Patch by Sean Rodman.

Lib/test/test_support.py

@@ -102,7 +102,7 @@ class TestSupport(unittest.TestCase):
                 self.assertTrue(os.path.isdir(path))
             self.assertFalse(os.path.isdir(path))
         finally:
-            shutil.rmtree(parent_dir)
+            support.rmtree(parent_dir)
 
     def test_temp_dir__path_none(self):
         """Test passing no path."""