The pollPVEInstance error path returned without touching node state, so
a host that stopped answering kept showing its last online snapshot
forever (#1441, reported against v5 in #1135), and a host that was
already down when Pulse started never appeared on the dashboard at all
(#1433).
Route the poll error through the same grace policy as the existing
empty-node fallback: nodes seen within the grace window keep their
prior state with degraded connection health, then flip to offline with
cleared uptime and CPU once the window lapses. An instance with no node
state yet gets the synthesized offline entry from removeFailedPVENode
so it still shows on the dashboard.
Backport of the v6 fixes 02955619f and 8372a22c5.
rcourtman
d70cf862ec