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>

plugin/environment_test.go

@@ -5,7 +5,6 @@ package plugin
 
 import (
 	"encoding/json"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"testing"
@@ -16,7 +15,7 @@ import (
 )
 
 func TestAvailablePlugins(t *testing.T) {
-	dir, err1 := ioutil.TempDir("", "mm-plugin-test")
+	dir, err1 := os.MkdirTemp("", "mm-plugin-test")
 	require.NoError(t, err1)
 	t.Cleanup(func() {
 		os.RemoveAll(dir)
@@ -40,7 +39,7 @@ func TestAvailablePlugins(t *testing.T) {
 		path := filepath.Join(dir, "plugin1", "plugin.json")
 		manifestJSON, jsonErr := json.Marshal(bundle1.Manifest)
 		require.NoError(t, jsonErr)
-		err = ioutil.WriteFile(path, manifestJSON, 0644)
+		err = os.WriteFile(path, manifestJSON, 0644)
 		require.NoError(t, err)
 
 		bundles, err := env.Available()
@@ -54,7 +53,7 @@ func TestAvailablePlugins(t *testing.T) {
 		defer os.RemoveAll(filepath.Join(dir, "plugin2"))
 
 		path := filepath.Join(dir, "plugin2", "manifest.json")
-		err = ioutil.WriteFile(path, []byte("{}"), 0644)
+		err = os.WriteFile(path, []byte("{}"), 0644)
 		require.NoError(t, err)
 
 		bundles, err := env.Available()