Ensure default routes are set for Istio services

Setting default routes in Istio is considered best practice. For more information on service routing, see the Istio documentation.
References:
https://istio.io/latest/docs/ops/best-practices/traffic-management/

Update your Istio YAML to include a VirtualService with a default route for each service. Make sure 'trafficPolicy' is added at top level (under spec) instead of individual subsets.