When the client is disconnected from control for any reason (typically
just turned off), we should still attempt to update if auto-updates are
enabled. This may help users who turn tailscale on infrequently for
accessing resources.
RELNOTE: Apply auto-updates even if the node is down or disconnected
from the coordination server.
Updates #12117
Signed-off-by: Andrew Lytvynov <awly@tailscale.com>