lxd-agent: Updates startStatusNotifier to return a cancel function
lxd-agent: Updates startStatusNotifier to return a cancel function

Allowing the STOPPED status to be written into the QEMU status ringbuffer synchronously.

And reduces tick interval to 5s.

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

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