Automatic merge from submit-queue
Fix deadlock possibility in federated informer
On cluster add subinformer locks and tries to add cluster to federated informer. When someone checks if everything is in sync federated informer is locked and then subinformer is inspected what apparently requires a lock. With really bad timing this can create a deadlock.
This PR ensures that there is always at most 1 lock taken in federated informer.
cc: @quinton-hoole @kubernetes/sig-cluster-federation
Fixes: #30855
b15c2d67e6