Increase cache size for endpointslices.

It should match what we have for endpoints as endpointslices is
replacing them and # updates of endpointslices should be roughly the
same as # updates of endpoints.

Otherwise, kube-proxy may start loosing watches for endpointslices (we believe this is
what currently happens in scale tests, will create an issue for that
soon).

pkg/registry/cachesize/cachesize.go

@@ -36,6 +36,7 @@ func NewHeuristicWatchCacheSizes(expectedRAMCapacityMB int) map[schema.GroupReso
 	watchCacheSizes := make(map[schema.GroupResource]int)
 	watchCacheSizes[schema.GroupResource{Resource: "replicationcontrollers"}] = maxInt(5*clusterSize, 100)
 	watchCacheSizes[schema.GroupResource{Resource: "endpoints"}] = maxInt(10*clusterSize, 1000)
+	watchCacheSizes[schema.GroupResource{Resource: "endpointslices", Group: "discovery.k8s.io"}] = maxInt(10*clusterSize, 1000)
 	watchCacheSizes[schema.GroupResource{Resource: "nodes"}] = maxInt(5*clusterSize, 1000)
 	watchCacheSizes[schema.GroupResource{Resource: "pods"}] = maxInt(50*clusterSize, 1000)
 	watchCacheSizes[schema.GroupResource{Resource: "services"}] = maxInt(5*clusterSize, 1000)