Kiali - Conditionally parse Istio registry based on version

In order for Kiali 1.73 to work with both istio 1.18 and istio 1.20, Kiali needs to conditionally parse the json from the internal istio registry based on the istio version since the response format changed from 1.18 to 1.20. See this comment for more details: https://github.com/kiali/kiali/issues/6510#issuecomment-1719692297.