Remove spammy logs in unit tests (#29825)
Remove spammy logs in unit tests (#29825)

This causes a bunch of logs like `klog  timed out waiting for caches to sync` in all of our tests,
which gets highlighted by Prow and obscures real errors. I don't think
we really need this log, it only happens when the stop channel is closed
so Istio is shutting down; no other controllers do it.
istio/istio,istio/istio,istio/istio,istio/istio,istio/istio