all: apply go fix

Updates #cleanup

Signed-off-by: Adriano Sela Aviles <adriano@tailscale.com>

ipn/ipnlocal/breaktcp_darwin.go

@@ -15,7 +15,7 @@ func init() {
 
 func breakTCPConnsDarwin() error {
 	var matched int
-	for fd := 0; fd < 1000; fd++ {
+	for fd := range 1000 {
 		_, err := unix.GetsockoptTCPConnectionInfo(fd, unix.IPPROTO_TCP, unix.TCP_CONNECTION_INFO)
 		if err == nil {
 			matched++

ipn/ipnlocal/local_test.go

@@ -2123,8 +2123,7 @@ func TestWatchNotificationsCallbacks(t *testing.T) {
 
 func TestWatchNotificationsClosesSlowConsumer(t *testing.T) {
 	b := newTestLocalBackend(t)
-	ctx, cancel := context.WithCancel(context.Background())
-	defer cancel()
+	ctx := t.Context()
 
 	watchAdded := make(chan struct{})
 	firstNotify := make(chan struct{}, 1)