Use plain Istio install (not operator)

[howardjohn]

Currently the tests are installing the Istio operator. That would not really matter much since the end result is the same, but the control plane memory/CPU resource utilization is including it which skews the results a bit. I would recommend either not using the operator (see https://istio.io/latest/docs/setup/install/operator/, its not recommended for prod), or only including istio-system in the metrics (possibly just set container=discovery since that is the only control plane container).

With this I see about 50% of the control plane memory reported in https://linkerd.io/2021/11/29/linkerd-vs-istio-benchmarks-2021/index.html