etcdserver: enable "CheckQuorum" when starting with "ForceNewCluster"

We enable "raft.Config.CheckQuorum" by default in other
Raft initial starts. So should start with "ForceNewCluster".

Signed-off-by: Gyuho Lee <gyuhox@gmail.com>

etcdserver/raft.go

@@ -500,6 +500,7 @@ func restartAsStandaloneNode(cfg ServerConfig, snapshot *raftpb.Snapshot) (types
 		Storage:         s,
 		MaxSizePerMsg:   maxSizePerMsg,
 		MaxInflightMsgs: maxInflightMsgs,
+		CheckQuorum:     true,
 	}
 	n := raft.RestartNode(c)
 	raftStatus = n.Status