Fix setupcheck for intl module

A polyfill for intl is loaded very early (somewhere in base). Polyfill defines grapheme_strlen as function if
intl extension is not loaded. The check here is always true
because there is a function with that name.

Signed-off-by: Daniel Kesselberg <mail@danielkesselberg.de>

settings/Controller/CheckSetupController.php

@@ -574,7 +574,7 @@ Raw output
 	protected function hasRecommendedPHPModules(): array {
 		$recommendedPHPModules = [];
 
-		if (!function_exists('grapheme_strlen')) {
+		if (!extension_loaded('intl')) {
 			$recommendedPHPModules[] = 'intl';
 		}