fix: ack vpc.delete-nat in tests so teardown doesn't wait out the 15 s request timeout

spinifex/daemon/daemon_system_instance_test.go

@@ -799,6 +799,7 @@ func TestLaunchSystemInstance_NATFailureRollsBackPublicIP(t *testing.T) {
 	// rule vpcd may have committed after the AddNAT timeout window.
 	deleteNATCh := make(chan map[string]string, 1)
 	delSub, err := d.natsConn.Subscribe("vpc.delete-nat", func(msg *nats.Msg) {
+		_ = msg.Respond([]byte(`{"success":true}`))
 		var p map[string]string
 		_ = json.Unmarshal(msg.Data, &p)
 		select {

spinifex/handlers/ec2/instance/service_impl_test.go

@@ -3882,6 +3882,7 @@ func TestPrepareRunInstances_NATFailureRollsBackPublicIP(t *testing.T) {
 	// half-committed rule from a waitForFlowsHV timeout.
 	deleteNATCh := make(chan natWirePayload, 1)
 	delSub, err := svc.natsConn.Subscribe("vpc.delete-nat", func(msg *nats.Msg) {
+		_ = msg.Respond([]byte(`{"success":true}`))
 		var p natWirePayload
 		_ = json.Unmarshal(msg.Data, &p)
 		select {
@@ -3989,6 +3990,7 @@ func TestPrepareRunInstances_PartialLaunchReleasesSucceededInstances(t *testing.
 
 	deleteNATCh := make(chan natWirePayload, 2)
 	delSub, err := svc.natsConn.Subscribe("vpc.delete-nat", func(msg *nats.Msg) {
+		_ = msg.Respond([]byte(`{"success":true}`))
 		var p natWirePayload
 		_ = json.Unmarshal(msg.Data, &p)
 		select {

spinifex/testutil/nats.go

@@ -101,6 +101,7 @@ var vpcdStubTopics = []string{
 	"vpc.update-port-sgs",
 	"vpc.create-port",
 	"vpc.delete-port",
+	"vpc.delete-nat",
 }
 
 // vpcdStubRegistry holds the per-conn response map. Per-conn so concurrent tests with separate conns don't interfere.