If multiple SMCPs exist in a namespace, the controller reconciles them all

Although the webhook prevents creating multiple SMCPs in the same namespace, the controller should still properly handle cases where multiple SMCPs exist. Currently, it tries to reconcile each SMCP, overwriting child resources every time.

Before reconciling an SMCP, the controller should check if that's the only SMCP in the namespace. If there are multiple, the controller should either reconcile only the oldest SMCP and report an error for all the others, or report an error in all of them.