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>

consensus/ethash/algorithm_test.go

@@ -698,6 +698,8 @@ func TestHashimoto(t *testing.T) {
 // Tests that caches generated on disk may be done concurrently.
 func TestConcurrentDiskCacheGeneration(t *testing.T) {
 	// Create a temp folder to generate the caches into
+	// TODO: t.TempDir fails to remove the directory on Windows
+	// \AppData\Local\Temp\1\TestConcurrentDiskCacheGeneration2382060137\001\cache-R23-1dca8a85e74aa763: Access is denied.
 	cachedir, err := ioutil.TempDir("", "")
 	if err != nil {
 		t.Fatalf("Failed to create temporary cache dir: %v", err)
@@ -794,11 +796,7 @@ func BenchmarkHashimotoFullSmall(b *testing.B) {
 
 func benchmarkHashimotoFullMmap(b *testing.B, name string, lock bool) {
 	b.Run(name, func(b *testing.B) {
-		tmpdir, err := ioutil.TempDir("", "ethash-test")
-		if err != nil {
-			b.Fatal(err)
-		}
-		defer os.RemoveAll(tmpdir)
+		tmpdir := b.TempDir()
 
 		d := &dataset{epoch: 0}
 		d.generate(tmpdir, 1, lock, false)