Update k8s_taints documentation and taints fixes

[naris-silpakit]

What does this PR do?

• Adds examples for k8_taints in the managed-node-group documentation files.
• Removes k8s_taints from examples that passed them into self-managed node groups as EKS only supports taints through managed node groups.
• Removes k8_taints local from the aws-eks-fargate-profile module locals.tf for the same reason as above, and it wasn't being used.

Motivation

Addressing a documentation request for k8s_taints for managed node groups. Thanks for reporting this schwichti!

More

• Yes, I have tested the PR using my local account setup (Provide any test evidence report under Additional Notes)
• Yes, I have added a new example under examples to support my PR
• Yes, I have created another PR for add-ons under add-ons repo (if applicable)
• Yes, I have updated the docs for this feature
• Yes, I ran pre-commit run -a with this PR

Note: Not all the PRs required examples and docs except a new pattern or add-on added.

For Moderators

• E2E Test successfully complete before merge?

[askulkarni2]

we should add support for self-managed via kubelet args.

[naris-silpakit]

we should add support for self-managed via kubelet args.

Hoping to keep the changes minor for this PR as it just clarifies the current functionality. I can look into adding taint support for self-managed node groups via the kubelet args as a separate new feature PR.

[askulkarni2]

Opened https://github.com/aws-ia/terraform-ssp-amazon-eks/issues/187 for self-managed support.

[vara-bonthu]

Closing the issue since the PR is merged now.