Add refcounting to avoid close connection by mistake

[kkewwei]

The connection will be closed by node-left task, at the same time the connection maybe have been reused by join request, This commit import refcounting to solve the problem.

Relates #67873

[DaveCTurner]

Unfortunately this will leak: we might call connectToNode multiple times while the isDeleting flag is set (e.g. handling multiple joins from the same node, or else an old PeerFinder might still be active). We need to make sure that every connectToNode call explicitly releases any references that it obtained.

[kkewwei]

I use reuse instead of refcounting to avoid excess count. When to close the connection depends on the reuse situation at that time.

It seems difficult to work out exactly when to release the ActionListener<Releasable> in TransportService#connectToNode.

[DaveCTurner]

Difficult, yes, but unfortunately it seems necessary too. I spent some time on this yesterday and although I'm not ready to open a PR you can see my work here: master...DaveCTurner:2021-09-01-releasable-connections. I think this gets the lifecycles about right, and I love how much it simplifies the NodeConnectionsService, but there's a few outstanding test issues still to resolve and I need to think about it some more with a fresh mind too.