Re: Change suggestion: more efficient replica state tracking

[Mark Miller]

Yeah, I took the DOWN state out all together in shutdown as its problematic
and effectively sugar for the user view of the cluster state - as far as
the system goes, if the ephemeral live node is gone, that node is down,
regardless of the replica state. There is some value in being able to
remove an individual replica from search (rather than the full node), but
even that doesn't require the DOWN state publishing on shutdown.