Drupal Core doesn't create an active config directory anymore

Drupal 8.0.x used to have a config directory where the current active configuration was saved, this has been changed with #2161591: Change default active config from file storage to DB storage but the directory was still existing.
This empty and not used directory caused confusion and therefore it is now removed.

Contrib or custom modules can create it again with defining the active directory in settings.php and this code:

$config_directory = config_get_config_directory(CONFIG_ACTIVE_DIRECTORY);
return file_prepare_directory($config_directory, FILE_CREATE_DIRECTORY | FILE_MODIFY_PERMISSIONS);

As part of this change, the method install_ensure_config_directory() has been deprecated. If your code is using this method, replace it with the same code as above for making the directory.