Multicluster-global-hub: multicluster-global-hub: manager trusts self-asserted evt.source() for leaf-hub identity in all status handlers

A flaw was found in multicluster-global-hub. The manager component improperly validates the source identity of incoming CloudEvents on Kafka status topics. A remote attacker, after compromising a managed hub and obtaining its Kafka client certificate, can manipulate the self-asserted source identity. This allows the attacker to falsify or delete critical data, such as compliance, inventory, and cluster health information, belonging to other hubs in the database.