With this change https://github.com/istio-ecosystem/sail-operator/pull/1054 , we can set test images for IBM via kustomization file instead of IDMS/ITMS. 

Create kustomization file for that and adapt the downstream pipeline.

More info: https://redhat-internal.slack.com/archives/C014C8Y0S64/p1754393011730269

Info about test images can be found here: https://docs.google.com/spreadsheets/d/1q5iykmpZMh6E1jrG6DW4Cq1KlUOW04y2hQ6YSxNxBug/edit?gid=2024850297#gid=2024850297