lxd/daemon: Don't remove offline members from supplied heartbeat member list in NodeRefreshTask
lxd/daemon: Don't remove offline members from supplied heartbeat member list in NodeRefreshTask

We may need to use the full list (including offline members) for other uses later.

Instead we are going to filter out offline members where it is appropriate.

As a result of this we lower the cluster role rebalance check from needing >2 members to >1 members.

Signed-off-by: Thomas Parrott <6b778ce645fb0e3dde76d79eccad490955b1ae74@canonical.com>

lxc/lxd,stgraber/lxd,hallyn/lxd,stgraber/lxd,stgraber/lxd,stgraber/lxd,lxc/lxd,lxc/lxd,lxc/lxd,hallyn/lxd,stgraber/lxd,hallyn/lxd,stgraber/lxd,hallyn/lxd,lxc/lxd,lxc/lxd,lxc/lxd,stgraber/lxd,hallyn/lxd,hallyn/lxd