os/exec: replace os.MkdirTemp with T.TempDir

Updates #45402

Change-Id: Idbd8067759d58bc57c52ede4ddccc98ab0ae18fc
Reviewed-on: https://go-review.googlesource.com/c/go/+/308129
Run-TryBot: Dave Cheney <[email protected]>
TryBot-Result: Go Bot <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>
Trust: Tobias Klauser <[email protected]>

Author: perillo

src/os/exec/lp_windows_test.go

@@ -306,12 +306,7 @@ var lookPathTests = []lookPathTest{
 }
 
 func TestLookPath(t *testing.T) {
-	tmp, err := os.MkdirTemp("", "TestLookPath")
-	if err != nil {
-		t.Fatal("TempDir failed: ", err)
-	}
-	defer os.RemoveAll(tmp)
-
+	tmp := t.TempDir()
 	printpathExe := buildPrintPathExe(t, tmp)
 
 	// Run all tests.
@@ -508,12 +503,7 @@ var commandTests = []commandTest{
 }
 
 func TestCommand(t *testing.T) {
-	tmp, err := os.MkdirTemp("", "TestCommand")
-	if err != nil {
-		t.Fatal("TempDir failed: ", err)
-	}
-	defer os.RemoveAll(tmp)
-
+	tmp := t.TempDir()
 	printpathExe := buildPrintPathExe(t, tmp)
 
 	// Run all tests.