k8s: update eni-max-pods mapping

[etungsten]

Issue number:
N/A

Description of changes:
Adds r6a instance types and others.

Testing done:
Built aws-k8s-1.23 AMI and launched r6a.large instance with AMI and observed the max-pods value was set correctly according to the eni-max-pods mapping.

bash-5.1# apiclient get settings.kubernetes.max-pods
{
  "settings": {
    "kubernetes": {
      "max-pods": 29
    }
  }
}

Terms of contribution:

By submitting this pull request, I agree that this contribution is dual-licensed under the terms of both the Apache License, version 2.0, and the MIT license.