Istio charts for 1.19.9 and 1.20.5 are incorrectly sourced. istio-ingress-* and istio-egress-* charts are considered "Legacy Gateway Helm charts"

[prasad-shirodkar]

Istio charts for 1.19.9 and 1.20.5 are incorrectly sourced. Example: refer https://github.com/oracle-cne/catalog/blob/release/2.0/charts/istio-base-1.19.9/Chart.yaml#L3C1-L4C31

# This version is never actually shipped. istio/release-builder will replace it at build-time
# with the appropriate version

istio-ingress-* and istio-egress-* charts are considered "Legacy Gateway Helm charts"

In catalog repo for istio 1.19.9 and 1.20.5, the chart directories (under charts) represented by istio-ingress-* and istio-egress-* are considered by upstream as Legacy Gateway Helm charts

Istio historically offered two different charts - manifests/charts/gateways/istio-ingress and manifests/charts/gateways/istio-egress. These are replaced by this chart. While not required, it is recommended all new users use this chart, and existing users migrate when possible.

This chart has the following benefits and differences:

• Designed with Helm best practices in mind (standardized values options, values schema, values are not all nested under gateways.istio-ingressgateway.*, release name and namespace taken into account, etc).
• Utilizes Gateway injection, simplifying upgrades, allowing gateways to run in any namespace, and avoiding repeating config for sidecars and gateways.
• Published to official Istio Helm repository.
• Single chart for all gateways (Ingress, Egress, East West).