lxd/container_lxc: improve log for export
lxd/container_lxc: improve log for export

Signed-off-by: Christian Brauner <48455ab3070520a2d174545c7239d6d0fabd9a83@canonical.com>

ollie314/lxd,akshaykarle/lxd,hallyn/lxd,chrisglass/lxd,mjeanson/lxd,akshaykarle/lxd,erikmack/lxd,hallyn/lxd,jsavikko/lxd,pcdummy/lxd,Skarlso/lxd,erikmack/lxd,techtonik/lxd,pcdummy/lxd,stgraber/lxd,lxc/lxd,hallyn/lxd,atxwebs/lxd,techtonik/lxd,stgraber/lxd,stgraber/lxd,lxc/lxd,atxwebs/lxd,erikmack/lxd,atxwebs/lxd,Skarlso/lxd,chrisglass/lxd,ollie314/lxd,pcdummy/lxd,stgraber/lxd,mjeanson/lxd,lxc/lxd,ollie314/lxd,techtonik/lxd,jsavikko/lxd,lxc/lxd,hallyn/lxd,chrisglass/lxd,jsavikko/lxd,stgraber/lxd,hallyn/lxd,lxc/lxd,mjeanson/lxd,georghopp/lxd,Skarlso/lxd,akshaykarle/lxd,stgraber/lxd,stgraber/lxd,hallyn/lxd,atxwebs/lxd,lxc/lxd,georghopp/lxd,georghopp/lxd,lxc/lxd,Skarlso/lxd