feat: bump kfam and controller images to 1.8.0-rc.2

[NohaIhab]

• closes https://github.com/canonical/notebook-operators/issues/309
• sets ISTIO_INGRESS_GATEWAY_PRINCIPAL env var in kubeflow-profiles and kubeflow-kfam containers
• sets the KFP_UI_PRINCIPAL env var in kubeflow-profiles and kubeflow-kfam containers
• sets the NOTEBOOK_CONTROLLER_PRINCIPAL env var in kubeflow-profiles container

Linked references where the env vars are used in kubeflow-profiles container and kubeflow-kfam container