Create ZK nodes container before starting CuratorCache

PathChildrenCache invoked EnsureContainers internally during start(), so
the parent znode existed when publishCurrentServer ran. CuratorCache does
not, so on a fresh ZK creatingParentsIfNeeded reaches ZKPaths.mkdirs with
the trailing-slash forPath argument and fails with
"Path must not end with / character", aborting Spring startup.

common/queue/src/main/java/org/thingsboard/server/queue/discovery/ZkDiscoveryService.java

@@ -241,6 +241,7 @@ public class ZkDiscoveryService implements DiscoveryService {
             client = CuratorFrameworkFactory.newClient(zkUrl, zkSessionTimeout, zkConnectionTimeout, new RetryForever(zkRetryInterval));
             client.start();
             client.blockUntilConnected();
+            client.createContainers(zkNodesDir);
             cache = CuratorCache.builder(client, zkNodesDir).build();
             cache.start();
             stopped = false;