Alphabetized imports in various docs.

Follow-up of d97cce3409 and 7d3fe36c62.

docs/topics/testing/advanced.txt

@@ -38,7 +38,7 @@ Example
 The following is a simple unit test using the request factory::
 
     from django.contrib.auth.models import AnonymousUser, User
-    from django.test import TestCase, RequestFactory
+    from django.test import RequestFactory, TestCase
 
     from .views import MyView, my_view
 

docs/topics/testing/tools.txt

@@ -1023,7 +1023,7 @@ If you want to use a different ``Client`` class (for example, a subclass
 with customized behavior), use the :attr:`~SimpleTestCase.client_class` class
 attribute::
 
-    from django.test import TestCase, Client
+    from django.test import Client, TestCase
 
     class MyTestClient(Client):
         # Specialized methods for your environment