Get old cluster info in raft storage

Reproduce steps:
1. Use raft as store, set only one peer in config-raft.yaml
2. Cluster version is 7 at present.
3. Add or delete a node in cluster to make the cluster version changed, new version is 8.
4. Log shows the cluster version changed correctly, but still _**get version 7 cluster info in syncClusterToNodes method**_.
5. Log shows version 7 cluster info was sent to nodes, not latest version 8.