spec: Unconditionally set ownership of /var/lib/libvirt/sanlock

spec: Unconditionally set ownership of /var/lib/libvirt/sanlock

The libvirt-lock-sanlock subpackage requires sanlock to be installed
first and the sanlock package creates the sanlock group on all distros
we care about in the spec file (Fedora and RHEL >= 7). Thus instead of
setting the ownership and permissions in a post scriptlet only when the
sanlock group exists we can just install the directory with the
appropriate metadata.

https://bugzilla.redhat.com/show_bug.cgi?id=1702758

Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
Acked-by: Michal Privoznik <mprivozn@redhat.com>