[ticket/11997] Fix redirect tests for mod rewrite

Controller routes that are supposed to link to parent directories can't be
tested as the links are incorrectly created depending on enabled mod rewrite
or not.

PHPBB3-11997

tests/functional/fixtures/ext/foo/bar/config/services.yml

@@ -5,6 +5,7 @@ services:
             - @controller.helper
             - @path_helper
             - @template
+            - @config
             - %core.root_path%
             - %core.php_ext%