wgengine/magicsock: disable portmapper in tunchan-faked tests

Most of the magicsock tests fake the network, simulating packets going
out and coming in. There's no reason to actually hit your router to do
UPnP/NAT-PMP/PCP during in tests. But while debugging thousands of
iterations of tests to deflake some things, I saw it slamming my
router. This stops that.

Updates #11762

Change-Id: I59b9f48f8f5aff1fa16b4935753d786342e87744
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

wgengine/magicsock/magicsock_test.go

@@ -171,6 +171,7 @@ func newMagicStackWithKey(t testing.TB, logf logger.Logf, l nettype.PacketListen
 	epCh := make(chan []tailcfg.Endpoint, 100) // arbitrary
 	conn, err := NewConn(Options{
 		Logf:                   logf,
+		DisablePortMapper:      true,
 		TestOnlyPacketListener: l,
 		EndpointsFunc: func(eps []tailcfg.Endpoint) {
 			epCh <- eps
@@ -376,9 +377,10 @@ func TestNewConn(t *testing.T) {
 
 	port := pickPort(t)
 	conn, err := NewConn(Options{
-		Port:          port,
-		EndpointsFunc: epFunc,
-		Logf:          t.Logf,
+		Port:              port,
+		DisablePortMapper: true,
+		EndpointsFunc:     epFunc,
+		Logf:              t.Logf,
 	})
 	if err != nil {
 		t.Fatal(err)
@@ -1242,6 +1244,7 @@ func newTestConn(t testing.TB) *Conn {
 	t.Helper()
 	port := pickPort(t)
 	conn, err := NewConn(Options{
+		DisablePortMapper:      true,
 		Logf:                   t.Logf,
 		Port:                   port,
 		TestOnlyPacketListener: localhostListener{},