[robustness tests] Consider adding Keys, Count to Kubernetes traffic generator #20623
Description
What would you like to be added?
Kubernetes traffic generator should use Count of Kubernetes-Etcd interface and invoke Ranges with keys_only to better simulate actual Kubernetes traffic.
It seems that keys_only Range calls will be unlikely in the future due to kubernetes/kubernetes#133873.
Work in kubernetes/kubernetes#132355 also replaced calls to Count so it is likely the work on this may no longer be needed/useful.