Replace deprecated ioutil with io and os (#20776)

* Replace ioutil with io and os

* Replace ioutil in utils/file.go

* Minor fix to tests and excluded files

Co-authored-by: Tim Scheuermann <tim.scheuermann@mattermost.com>
Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

app/email/helper_test.go

@@ -5,7 +5,6 @@ package email
 
 import (
 	"bytes"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"testing"
@@ -64,7 +63,7 @@ func SetupWithStoreMock(tb testing.TB) *TestHelper {
 }
 
 func setupTestHelper(s store.Store, tb testing.TB) *TestHelper {
-	tempWorkspace, err := ioutil.TempDir("", "userservicetest")
+	tempWorkspace, err := os.MkdirTemp("", "userservicetest")
 	if err != nil {
 		panic(err)
 	}