After NC restart, report on non-running instances

Until now, if NC restarts, it will "adopt" and will report on
running instances, but will clean up any state left over from
instances no longer running. Among other things, that meant
if NC host is rebooted, instances that were running prior to
reboot simply "disappeared" from the point of view of CC or CLC.
Such instances were considered "running" by the CLC for a long
time (2-12 hours, depending on the version).

With this change, NC will pick up disk state from instances
no longer running and will report them in 'Teardown' state for
the duration of the teardown timeout.

Fixes (hopefully) EUCA-6039, EUCA-6086