increase LRU cache size 8x for authorization webhook
increase LRU cache size 8x for authorization webhook

1024 seems absurdly small for any normal deployment. At our 10000 byte
entry size limit, this will consume max ~80 MB of memory. More realistic
entry sizes are going to be less than a kB.

Kubernetes-commit: fb33b2f42a9621e65883c92a3cb49a278d14c6cc

kubernetes/apiserver,kubernetes/apiserver