Update Dockerfile_leap

Signed-off-by: Shubhangi-dell <shubhangi_srivastava@dell.com>

control_plane/roles/provision_cobbler/files/Dockerfile_leap

@@ -1,4 +1,4 @@
-FROM registry.opensuse.org/opensuse/leap:15.3
+FROM registry.opensuse.org/opensuse/leap:docker_os
 
 #Enable all repose
 RUN zypper mr -ea
@@ -67,4 +67,4 @@ VOLUME [ "/srv/www/cobbler", "/var/lib/cobbler/backup", "/mnt" ]
 
 RUN systemctl enable dhcpd
 
-CMD ["sbin/init"]
+CMD ["sbin/init"]