As explained in the NetIQ iManager Installation Guide, the iManager instructions for dealing with self-signed certificates don’t apply to OES Linux.
OES installs Tomcat and Apache versions that are specific to OES (see Section 6.14, Novell-tomcat Is for OES Use Only). For instructions on replacing the self-signed Apache/Tomcat certificate on OES, see Section 23.2, Setting Up Certificate Management.