test: use T.TempDir to create temporary test directory (#15400)

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`
needs 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>

internal/disk/disk_test.go

@@ -21,21 +21,13 @@
 package disk_test
 
 import (
-	"io/ioutil"
-	"os"
 	"testing"
 
 	"github.com/minio/minio/internal/disk"
 )
 
 func TestFree(t *testing.T) {
-	path, err := ioutil.TempDir(os.TempDir(), "minio-")
-	defer os.RemoveAll(path)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	di, err := disk.GetInfo(path)
+	di, err := disk.GetInfo(t.TempDir())
 	if err != nil {
 		t.Fatal(err)
 	}