Reverse proxy: Skip flaky test for 5xx status codes (#95839)

add 5xx status codes

pkg/util/proxyutil/reverse_proxy_test.go

@@ -166,6 +166,7 @@ func TestReverseProxy(t *testing.T) {
 	})
 
 	t.Run("5xx response status codes should set downstream status source", func(t *testing.T) {
+		t.Skip("Skip for flaky test")
 		testCases := []struct {
 			status         int
 			expectedSource requestmeta.StatusSource