clustermesh: write services synced canary into etcd

This commit includes the glue logic to write the "synced" canary when
the initial synchronization from k8s completes. The corresponding
capability is not yet turned on in the CiliumClusterConfig, because
"synced" canaries need still to be enabled for the other resource types.

Signed-off-by: Marco Iorio <marco.iorio@isovalent.com>

operator/watchers/k8s_service_sync.go

@@ -183,6 +183,14 @@ func StartSynchronizingServices(ctx context.Context, wg *sync.WaitGroup, clients
 		}()
 	}
 
+	go func() {
+		<-k8sSvcCacheSynced
+		cache.WaitForCacheSync(ctx.Done(), endpointController.HasSynced)
+
+		log.Info("Initial list of services successfully received from Kubernetes")
+		kvs.Synced(ctx)
+	}()
+
 	wg.Add(1)
 	go func() {
 		defer wg.Done()