IncludeRule: sort files in included directory

... instead of relying on the filesystem(!) ordering, which will look
random to both users and unittests.

Also partially revert the test changes from
c5a7bcd50e /
https://gitlab.com/apparmor/apparmor/-/merge_requests/548 -
sorting the result only in the tests is a bad idea.

utils/apparmor/rule/include.py

@@ -138,7 +138,7 @@ class IncludeRule(BaseRule):
         files = []
 
         if os.path.isdir(full_path):
-            for path in os.listdir(full_path):
+            for path in sorted(os.listdir(full_path)):
                 if is_skippable_file(path):
                     continue