Run go generate and go vet on all packages (#30529)

Fixes: https://github.com/go-gitea/gitea/issues/30512

I think this does mean those tools would run on a potential `vendor`
directory, but I'm not sure we really support vendoring of dependencies
anymore.

`release` has a `vendor` prerequisite so likely the source tarballs
contain vendor files?

tests/integration/api_issue_attachment_test.go

@@ -1,6 +1,5 @@
 // Copyright 2021 The Gitea Authors. All rights reserved.
-// Use of this source code is governed by a MIT-style
-// license that can be found in the LICENSE file.
+// SPDX-License-Identifier: MIT
 
 package integration