[FEATURE] Use EKS new access management

Right now, the implementation uses `aws-auth` `ConfigMap` for managing access to EKS clusters. This issue is for migrating to EKS new access management announced recently -- see: https://aws.amazon.com/blogs/containers/a-deep-dive-into-simplified-amazon-eks-access-management-controls/.

Update the implementation at `repos/gitops-system/tools-config/aws-auth`. The official Upbound AWS provider has MR for managing access using the new mechanism. See: https://marketplace.upbound.io/providers/upbound/provider-aws-eks/v1.4.0/resources/eks.aws.upbound.io/ClusterAuth/v1beta1.