enforce explanation for necessary nolints and fix bugs (#34883)

Follows up https://github.com/go-gitea/gitea/pull/34851

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

contrib/backport/backport.go

@@ -1,7 +1,7 @@
 // Copyright 2023 The Gitea Authors. All rights reserved.
 // SPDX-License-Identifier: MIT
 
-//nolint:forbidigo
+//nolint:forbidigo // use of print functions is allowed in cli
 package main
 
 import (