`ingress.class` annotation is deprecated

[AlexanderBrevig]

https://kubernetes.io/blog/2020/04/02/improvements-to-the-ingress-api-in-kubernetes-1.18/#deprecating-the-ingress-class-annotation

https://github.com/entur/helm-charts/blob/main/charts/common/templates/ingress.yaml#L16

[sindrel]

I think we should consider the possibility of removing the ingress.class annotation, in favor of setting a cluster default ingress class:
https://kubernetes.io/docs/concepts/services-networking/ingress/#default-ingress-class