On phpBB's master version when you have too many incorrect login attempts the login page throws a 500 error because it tries to init() the captcha with `2` instead of the now required `confirm_type` enum.

phpbb\captcha\plugins\legacy_wrapper::init(): Argument #1 ($type) must be of type phpbb\captcha\plugins\confirm_type, int given, called in /phpbb/phpBB/includes/functions.php on line 2411

We should use the enum value instead of the deprecated constant.