test: replace ensure.TempDir with t.TempDir

This commit replaces `ensure.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 `ensure.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>

pkg/chartutil/save_test.go

@@ -29,14 +29,12 @@ import (
 	"testing"
 	"time"
 
-	"helm.sh/helm/v3/internal/test/ensure"
 	"helm.sh/helm/v3/pkg/chart"
 	"helm.sh/helm/v3/pkg/chart/loader"
 )
 
 func TestSave(t *testing.T) {
-	tmp := ensure.TempDir(t)
-	defer os.RemoveAll(tmp)
+	tmp := t.TempDir()
 
 	for _, dest := range []string{tmp, filepath.Join(tmp, "newdir")} {
 		t.Run("outDir="+dest, func(t *testing.T) {