*: use T.TempDir to create temporary test directory

The directory created by `T.TempDir()` and is automatically removed when
the test and all its subtests complete.

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

client/pkg/fileutil/read_dir_test.go

@@ -22,11 +22,7 @@ import (
 )
 
 func TestReadDir(t *testing.T) {
-	tmpdir, err := os.MkdirTemp("", "")
-	defer os.RemoveAll(tmpdir)
-	if err != nil {
-		t.Fatalf("unexpected os.MkdirTemp error: %v", err)
-	}
+	tmpdir := t.TempDir()
 
 	files := []string{"def", "abc", "xyz", "ghi"}
 	for _, f := range files {