Add a "Service Discovery Collector Image" field to the Resilience Testing Image Registry — so that the custom service-discovery-collector image can be centrally managed alongside the other RT/DDCR images, in a single place, consistent with how Resilience Testing releases document all five images together.

Add a "Resilience Testing Images" toggle to the Discovery Agent custom image configuration:

When toggled OFF: the existing custom image fields are presented and can be completed individually (current behavior).

When toggled ON: the custom image fields are hidden/greyed out, and the Discovery Agent automatically inherits the service-discovery-collector image configured in the Resilience Testing Image Registry.

This design would allow Resilience Testing-related Discovery Agents to use the centralized RT custom image configuration, while keeping non-RT Discovery Agents fully independent — a clean and logical separation.