Handle ioutil deprecations (#53526)

* replace ioutil.ReadFile -> os.ReadFile

* replace ioutil.ReadAll -> io.ReadAll

* replace ioutil.TempFile -> os.CreateTemp

* replace ioutil.NopCloser -> io.NopCloser

* replace ioutil.WriteFile -> os.WriteFile

* replace ioutil.TempDir -> os.MkdirTemp

* replace ioutil.Discard -> io.Discard

pkg/setting/expanders.go

@@ -2,7 +2,6 @@ package setting
 
 import (
 	"fmt"
-	"io/ioutil"
 	"os"
 	"regexp"
 	"sort"
@@ -145,7 +144,7 @@ func (e fileExpander) Expand(s string) (string, error) {
 
 	// nolint:gosec
 	// We can ignore the gosec G304 warning on this one because `s` comes from configuration section keys
-	f, err := ioutil.ReadFile(s)
+	f, err := os.ReadFile(s)
 	if err != nil {
 		return "", err
 	}

pkg/setting/expanders_test.go

@@ -3,7 +3,6 @@ package setting
 import (
 	"errors"
 	"fmt"
-	"io/ioutil"
 	"math/rand"
 	"os"
 	"testing"
@@ -35,7 +34,7 @@ func TestExpandVar_EnvSuccessful(t *testing.T) {
 }
 
 func TestExpandVar_FileSuccessful(t *testing.T) {
-	f, err := ioutil.TempFile(os.TempDir(), "file expansion *")
+	f, err := os.CreateTemp(os.TempDir(), "file expansion *")
 	require.NoError(t, err)
 	file := f.Name()