feat: include kube-ovn v1.15.4 image in iso packaging

Signed-off-by: Zespre Chang <zespre.chang@suse.com>

Author: starbops

scripts/images/harvester-additional-images.txt

@@ -1,3 +1,3 @@
 registry.suse.com/suse/vmdp/vmdp:2.5.5
-docker.io/kubeovn/kube-ovn:v1.14.10
+docker.io/kubeovn/kube-ovn:v1.15.4
 registry.k8s.io/descheduler/descheduler:v0.33.0