Change AWS Kubenetes provider authentication to use data.eks_cluster instead of exec

[costrouc]

Fixes | Closes | Resolves #1106

Changes introduced in this PR:

• this PR changes the aws credentials from being stored and used by each stage to instead being fetched each time the kubernetes provider is used (using data).

This follows best practices outlined in https://github.com/hashicorp/terraform-provider-kubernetes/tree/main/_examples/eks. Later we may want to adopt this for other clouds.

Types of changes

These changes should not add or remove any features.

Put an x in the boxes that apply

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds a feature)
• Breaking change (fix or feature that would cause existing features to not work as expected)
• Documentation Update
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no API changes)
• Build related changes
• Other (please describe):

Testing

Requires testing

• Yes
• No