p2p/nat: remove test with default servers (#31225)

The test occasionally fails when network connectivity is bad or if it
hits the wrong server. We usually don't add tests with external network
dependency so I'm removing them.

Fixes #31220

Author: fjl

p2p/nat/stun_test.go

@@ -18,17 +18,8 @@ package nat
 
 import (
 	"testing"
-
-	"github.com/stretchr/testify/assert"
 )
 
-func TestNatStun(t *testing.T) {
-	nat, err := newSTUN("")
-	assert.NoError(t, err)
-	_, err = nat.ExternalIP()
-	assert.NoError(t, err)
-}
-
 func TestUnreachedNatServer(t *testing.T) {
 	stun := &stun{
 		serverList: []string{"198.51.100.2:1234", "198.51.100.5"},