Internal: Revert PHP 8 compatibility improvement in api_htmlentities(…

…) as it causes issues filtering HTML tags in HTML titles - refs BT#22321

main/inc/lib/internationalization.lib.php

@@ -1207,7 +1207,7 @@ function api_htmlentities($string, $quote_style = ENT_COMPAT, $encoding = 'UTF-8
             break;
     }
 
-    return htmlspecialchars($string);
+    return mb_convert_encoding($string, 'HTML-ENTITIES', 'UTF-8');
 }
 
 /**