Fix VM Agent RBAC warnings (#5391)

Recent changes for K8s Node cause VM Agent RBAC warnings regarding
service and node. These warnings will flood VM Agent logs.

This change fixes the issue by only initializing the related components
for K8s Node case.

Signed-off-by: Mengdie Song <songm@vmware.com>

cmd/antrea-agent/agent.go

@@ -140,8 +140,10 @@ func run(o *Options) error {
 	enableMulticlusterGW := features.DefaultFeatureGate.Enabled(features.Multicluster) && o.config.Multicluster.EnableGateway
 	enableMulticlusterNP := features.DefaultFeatureGate.Enabled(features.Multicluster) && o.config.Multicluster.EnableStretchedNetworkPolicy
 	enableFLowExporter := features.DefaultFeatureGate.Enabled(features.FlowExporter) && o.config.FlowExporter.Enable
-
-	nodeIPTracker := nodeip.NewTracker(nodeInformer)
+	var nodeIPTracker *nodeip.Tracker
+	if o.nodeType == config.K8sNode {
+		nodeIPTracker = nodeip.NewTracker(nodeInformer)
+	}
 	// Bridging mode will connect the uplink interface to the OVS bridge.
 	connectUplinkToBridge := enableBridgingMode
 	ovsDatapathType := ovsconfig.OVSDatapathType(o.config.OVSDatapathType)
@@ -169,14 +171,15 @@ func run(o *Options) error {
 	)
 
 	var serviceCIDRNet *net.IPNet
+	var serviceCIDRProvider *servicecidr.Discoverer
 	if o.nodeType == config.K8sNode {
 		_, serviceCIDRNet, _ = net.ParseCIDR(o.config.ServiceCIDR)
+		serviceCIDRProvider = servicecidr.NewServiceCIDRDiscoverer(serviceInformer)
 	}
 	var serviceCIDRNetv6 *net.IPNet
 	if o.config.ServiceCIDRv6 != "" {
 		_, serviceCIDRNetv6, _ = net.ParseCIDR(o.config.ServiceCIDRv6)
 	}
-	serviceCIDRProvider := servicecidr.NewServiceCIDRDiscoverer(serviceInformer)
 
 	_, encapMode := config.GetTrafficEncapModeFromStr(o.config.TrafficEncapMode)
 	_, encryptionMode := config.GetTrafficEncryptionModeFromStr(o.config.TrafficEncryptionMode)
@@ -232,8 +235,10 @@ func run(o *Options) error {
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
 
-	// Must start after registering all event handlers.
-	go serviceCIDRProvider.Run(stopCh)
+	if o.nodeType == config.K8sNode {
+		// Must start after registering all event handlers.
+		go serviceCIDRProvider.Run(stopCh)
+	}
 
 	// Get all available NodePort addresses.
 	var nodePortAddressesIPv4, nodePortAddressesIPv6 []net.IP