Fix #9036: Message confirm_custom_field_unlinking has confusing text.

Updated text to 'Are you sure you want to unlink this custom field from the project? The values will not be deleted as long as the custom field itself is not deleted.'

lang/strings_english.txt

@@ -1306,7 +1306,7 @@ $s_confirm_used_custom_field_deletion = 'This field is currently linked to at le
 $s_confirm_custom_field_deletion = 'Are you sure you want to delete this custom field and all associated values?';
 $s_field_delete_button = 'Delete Field';
 
-$s_confirm_custom_field_unlinking = 'Are you sure you want to remove (unlink) this custom field from the project and delete all associated values?';
+$s_confirm_custom_field_unlinking = 'Are you sure you want to unlink this custom field from the project? The values will not be deleted as long as the custom field itself is not deleted.';
 $s_field_remove_button = 'Remove Field';
 
 $s_hide_status = 'Hide Status';