wgengine/magicsock: disable legacy behavior in a few more tests.

Signed-off-by: David Anderson <danderson@tailscale.com>

wgengine/magicsock/magicsock_test.go

@@ -339,6 +339,7 @@ func TestNewConn(t *testing.T) {
 		Port:                    port,
 		EndpointsFunc:           epFunc,
 		Logf:                    t.Logf,
+		DisableLegacyNetworking: true,
 	})
 	if err != nil {
 		t.Fatal(err)
@@ -514,6 +515,7 @@ func TestDeviceStartStop(t *testing.T) {
 	conn, err := NewConn(Options{
 		EndpointsFunc:           func(eps []string) {},
 		Logf:                    t.Logf,
+		DisableLegacyNetworking: true,
 	})
 	if err != nil {
 		t.Fatal(err)
@@ -578,6 +580,7 @@ func TestConnClosing(t *testing.T) {
 			epCh <- eps
 		},
 		SimulatedNetwork:        false,
+		DisableLegacyNetworking: true,
 	})
 	if err != nil {
 		t.Fatalf("constructing magicsock: %v", err)