pmxcfs: do not grant LXC configs o+r permissions anymore

pmxcfs: do not grant LXC configs o+r permissions anymore

This was initially done because of some hook reading the config from
an unprivileged namespace when using unprivileged containers.

But, we nowadays do not do this anymore, either setup stuff before to
or use another source for getting required information (e.g., our
autodev hook uses "/var/lib/lxc/$vmid/devices").

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>