all: use T.TempDir to create temporary test directories (#24633)

This commit replaces ioutil.TempDir with t.TempDir in tests. The
directory created by t.TempDir is automatically removed when the test
and all its subtests complete.

Prior to this commit, temporary directory created using ioutil.TempDir
had to be removed manually by calling os.RemoveAll, which is omitted in
some tests. The error handling boilerplate e.g.

	defer func() {
		if err := os.RemoveAll(dir); err != nil {
			t.Fatal(err)
		}
	}

is also tedious, but t.TempDir handles this for us nicely.

Reference: https://pkg.go.dev/testing#T.TempDir
Signed-off-by: Eng Zer Jun <engzerjun@gmail.com>

console/console_test.go

@@ -20,7 +20,6 @@ import (
 	"bytes"
 	"errors"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"strings"
 	"testing"
@@ -88,10 +87,7 @@ type tester struct {
 // Please ensure you call Close() on the returned tester to avoid leaks.
 func newTester(t *testing.T, confOverride func(*ethconfig.Config)) *tester {
 	// Create a temporary storage for the node keys and initialize it
-	workspace, err := ioutil.TempDir("", "console-tester-")
-	if err != nil {
-		t.Fatalf("failed to create temporary keystore: %v", err)
-	}
+	workspace := t.TempDir()
 
 	// Create a networkless protocol stack and start an Ethereum service within
 	stack, err := node.New(&node.Config{DataDir: workspace, UseLightweightKDF: true, Name: testInstance})