* ignore PubSub Status message from unknown node, #20846
Reproducer:
1. old cluster of node1, node2 and node3
2. shutdown node3 and start it again with same host:port, let it
join itself and not the old cluster
3. node1 and node2 will continue to gossip to the node3 address and
Status message is accepted and replied to (Delta is ignored from
unknown node)
Solution:
* ignore status message from unknown node
* also added a reply flag in the Status message to break the
back-and-forth replies in case the deltas are not accepted,
this is not needed for fixing this bug, but it adds an extra
level of safety
