bugfix: hostgroups/num_services: remove <lambda>
bugfix: hostgroups/num_services: remove <lambda>

A <lambda> function was returned instead of the correct value.

shinken-monitoring/mod-livestatus,staute/shinken-mod-livestatus,shinken-monitoring/mod-livestatus,kaji-project/shinken-mod-livestatus,kaji-project/shinken-mod-livestatus,staute/shinken-mod-livestatus