Automatic merge from submit-queue

Fixing federation secret controller unit test flakiness

Fixes https://github.com/kubernetes/kubernetes/issues/36422

Adding a wait for the secret to be updated in the store to fix flakiness.
It was failing ~once in 3 to 5 runs before this change. I now have had 30 local runs without a failure.

cc @kubernetes/sig-cluster-federation @mwielgus