Use a distinctive app.kubernetes.io/name for the gateway Helm chart

Description

The gateway-helm-chart sets app.kubernetes.io/name from the chart name, which is currently gateway (Chart.yaml). This value is too generic: in any cluster also running Envoy Gateway, Istio, NGINX, etc., a selector like -l app.kubernetes.io/name=gateway is ambiguous and risks collisions, and it is a weak application identity.

Proposed changes:

• Use a distinctive app.kubernetes.io/name, e.g. apip-gateway — aligns with the existing APIP_ / APIP_GW_ config prefix and stays parallel to the sibling event-gateway chart.
• Add app.kubernetes.io/part-of: wso2-api-platform to the standard label set so the WSO2/product grouping is recorded in the conventionally-correct label (vendor/product belongs in part-of, not name).

Considerations:

• app.kubernetes.io/name is also a selector label (used in gateway-operator.selectorLabels), so it is immutable on existing releases — this should be decided before GA, as changing it later requires uninstall/reinstall.
• The chart name and the label are coupled (the label defaults to .Chart.Name). Renaming the chart in Chart.yaml also changes the published OCI artifact name and resource-name prefix. If only the label should change, set the default via nameOverride and leave Chart.yaml as is.

Version

No response

Related Issue

#2179

Start with the gateway-helm-chart Chart.yaml and the gateway-operator.selectorLabels usage to trace how the chart name supplies app.kubernetes.io/name. Compare the sibling event-gateway chart and decide whether a nameOverride preserves the chart and OCI artifact names. Done means the gateway uses a distinctive name and includes app.kubernetes.io/part-of: wso2-api-platform without breaking immutable selectors.