lxd/apparmor: Tweak default set of rules
lxd/apparmor: Tweak default set of rules

This should help with recent systemd unprivileged containers.

It also cleans up comments on most of our rules and better groups them
together.

Closes #5439

Signed-off-by: Stéphane Graber <089afc6d81f66f1168a9849e15660feae286e024@ubuntu.com>

lxc/lxd,Skarlso/lxd,atxwebs/lxd,stgraber/lxd,hallyn/lxd,stgraber/lxd,lxc/lxd,hallyn/lxd,lxc/lxd,hallyn/lxd,lxc/lxd,lxc/lxd,Skarlso/lxd,hallyn/lxd,stgraber/lxd,stgraber/lxd,stgraber/lxd,Skarlso/lxd,lxc/lxd,atxwebs/lxd,hallyn/lxd,atxwebs/lxd,mjeanson/lxd,stgraber/lxd,lxc/lxd,mjeanson/lxd,stgraber/lxd,mjeanson/lxd,hallyn/lxd,atxwebs/lxd,Skarlso/lxd