Refactor null coalescing operator in field mapping

Replaced the ternary shorthand (`?:`) with the null coalescing operator (`??`) for better readability and PHP compatibility. This ensures a cleaner handling of missing array keys or null values.

dca/tl_form_field.php

@@ -57,7 +57,7 @@
         {
             if ( $arrField['type'] !== 'index' )
             {
-                $arrFields[$arrField['name']] = $GLOBALS['TL_LANG']['tl_anystores'][$arrField['name']][0] ?: $arrField['name'];
+                $arrFields[$arrField['name']] = $GLOBALS['TL_LANG']['tl_anystores'][$arrField['name']][0] ?? $arrField['name'];
             }
         }