It was required by nethserver-adagios which is not supported on NethServer7:
nethserver-ocsinventory, nethserver-adagios: due to compatibility problems with Nagios, these modules will be mantained only on NethServer 6 release
If nethserver-adagios is no longer installed (due to the upgrade), there might be some remnants that shall be safe to remove (like /etc/httpd/conf.d/pnp4nagios.conf).