Upgrade to aws-load-balancer-controller v2

[irvingpop]

We're on the ALB ingress controller (v1). The same project has changed its name to the AWS Load Balancer Controller and very recently cut a v2 release. It's brand new so we should let it bake a while in the wild.

A good reason to upgrade to v2 is IngressGroup feature, which lets you share ALBs between namespaces. This would allow us to reduce our ALBs down to just 1, saving some monthly spend. Described here

Handy links:

• Installation docs from AWS: https://docs.aws.amazon.com/eks/latest/userguide/alb-ingress.html
• GH releases page: https://github.com/kubernetes-sigs/aws-load-balancer-controller/releases
• v1 to v2 migration guide: https://github.com/kubernetes-sigs/aws-load-balancer-controller/blob/main/docs/guide/upgrade/migrate_v1_v2.md