don't query prod poets in node tests and add timeout (#6698)

## Motivation

Unit tests in node_test.go query prod poets in `NewPoetServiceWithClient()` and might timeout if poet is not responding.

activation/poet.go

@@ -462,7 +462,10 @@ func NewPoetServiceWithClient(
 		opt(service)
 	}
 
-	err := service.verifyPhaseShiftConfiguration(context.Background())
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second*30)
+	defer cancel()
+
+	err := service.verifyPhaseShiftConfiguration(ctx)
 	switch {
 	case errors.Is(err, errIncompatiblePhaseShift):
 		logger.Fatal("failed to create poet service", zap.String("poet", client.Address()))

node/node_test.go

@@ -1253,6 +1253,8 @@ func getTestDefaultConfig(tb testing.TB) *config.Config {
 	cfg.POST.LabelsPerUnit = 32
 	cfg.POST.K2 = 4
 
+	cfg.BaseConfig.PoetServers = nil
+
 	cfg.SMESHING = config.DefaultSmeshingConfig()
 	cfg.SMESHING.Start = false
 	cfg.SMESHING.CoinbaseAccount = types.GenerateAddress([]byte{1}).String()