[Feature] flag to enable service discovery cleanup

Current State: Instances correctly deregistered, but dont see the default namespace and services cleaned up outside of that

Desired state: Want the ability to allow the controller to properly clean up all resources it created. The tutorial currently gives cloud map full access, so would follow that still.

Use case: We use SD for other things like ECS services though and eventually want to have a shared namespace controlled by IaC. At that point if we destroyed the stack and there were orphaned services from the k8s controller our IaC would fail to delete the SD namespace

No files, tests, or entry points are identified. Start by locating the controller's existing deregistration and service-discovery cleanup path, then determine where a cleanup flag belongs and verify that enabled cleanup removes all controller-created resources without disrupting shared namespaces or services.

Written by the indexing model from the issue text.