Do not install openstack-quantum-openvswitch-agent in server recipe

This is as SUSE-only fix (Ubuntu code path isn't affected). The
openstack-quantum-openvswitch-agent package is already installed as part
of the common_install recipe.

As a side-effect, this fixes the CHEF-3694 caused by this package being
installed twice:

WARN: Cloning resource attributes for package[openstack-quantum-openvswitch-agent] from prior resource (CHEF-3694)
WARN: Previous package[openstack-quantum-openvswitch-agent]: /var/chef/cache/cookbooks/quantum/recipes/server.rb:24:in `from_file'
WARN: Current  package[openstack-quantum-openvswitch-agent]: /var/chef/cache/cookbooks/quantum/recipes/common_install.rb:47:in `from_file'