redhat: Use SB cert from system-sb-certs for signing UKI
JIRA: INTERNAL Upstream Status: RHEL only
redhat-sb-certs-9.4-0.1.el9 and centos-sb-certs-9.0-23.el9 include SB cert for signing UKI so there's no need to have a copy in kernel anymore.
Signed-off-by: Vitaly Kuznetsov vkuznets@redhat.com