Description of problem:
CentOS 7 is using rhnsd.init instead of rhnsd.service
and appropriate service definition file is missing from rpm

Version-Release number of selected component (if applicable):
# rpm -qvil rhnsd
Name        : rhnsd
Version     : 5.0.37
Release     : 1.el7.centos
-rwxr-xr-x    1 root    root                     2437 Mar 19 10:51 /etc/rc.d/init.d/rhnsd
drwxr-xr-x    2 root    root                        0 Mar 19 11:02 /etc/sysconfig/rhn
-rw-r--r--    1 root    root                       13 Mar 19 10:51 /etc/sysconfig/rhn/rhnsd
-rwxr-xr-x    1 root    root                    19632 Mar 19 11:02 /usr/sbin/rhnsd
drwxr-xr-x    2 root    root                        0 Mar 19 11:02 /usr/share/doc/rhnsd-5.0.37
-rw-r--r--    1 root    root                    18092 Mar 19 10:51 /usr/share/doc/rhnsd-5.0.37/LICENSE
-rw-r--r--    1 root    root                      417 Mar 19 11:02 /usr/share/locale/foobars
-rw-r--r--    1 root    root                     1458 Mar 19 11:02 /usr/share/man/man8/rhnsd.8.gz

Actual results:

# systemctl status rhnsd
● rhnsd.service - LSB: Starts the Spacewalk Daemon
   Loaded: loaded (/etc/rc.d/init.d/rhnsd; bad; vendor preset: disabled)
   Active: active (running) since Mon 2018-06-11 10:09:01 CEST; 4h 45min ago
     Docs: man:systemd-sysv-generator(8)
  Process: 18735 ExecStop=/etc/rc.d/init.d/rhnsd stop (code=exited, status=0/SUCCESS)
  Process: 18746 ExecStart=/etc/rc.d/init.d/rhnsd start (code=exited, status=0/SUCCESS)
 Main PID: 18755 (rhnsd)
   CGroup: /system.slice/rhnsd.service
           └─18755 rhnsd


Expected results:

# systemctl status rhnsd
● rhnsd.service - Spacewalk Server daemon
   Loaded: loaded (/usr/lib/systemd/system/rhnsd.service; enabled; vendor preset: disabled)
   Active: active (running) since Tue 2018-06-05 11:50:12 CEST; 6 days ago
 Main PID: 6602 (rhnsd)
   CGroup: /system.slice/rhnsd.service
           └─6602 rhnsd