gitlab-ci.d/buildtest: Mark the aarch64 and ppc64-s390x CFI jobs as manual

gitlab-ci.d/buildtest: Mark the aarch64 and ppc64-s390x CFI jobs as manual

These two jobs are currently failing very often - the linker seems to
get killed due to out-of-memory problems. Since apparently nobody has
currently an idea how to fix that nicely, let's mark the jobs as manual
for the time being until someone comes up with a proper fix.

Message-Id: <20210728075141.400816-1-thuth@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Willian Rampazzo <willianr@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>