test: use T.TempDir to create temporary test directory

The directory created by `T.TempDir` 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>

integration/shim_dial_unix_test.go

@@ -150,10 +150,7 @@ func testFailFastWhenConnectShim(abstract bool, dialFn dialFunc) func(*testing.T
 }
 
 func newTestListener(t testing.TB, abstract bool) (string, net.Listener, func()) {
-	tmpDir, err := os.MkdirTemp("", "shim-ut-XX")
-	if err != nil {
-		t.Fatalf("failed to create tmp directory: %v", err)
-	}
+	tmpDir := t.TempDir()
 
 	// NOTE(fuweid):
 	//