docs: Replace cluster autoscaler/node termination handler example with Karpenter

[bryantbiggs]

Description

• Replace cluster autoscaler/node termination handler example with Karpenter

Motivation and Context

• Karpenter handles what cluster autoscaler and node termination previously provided and is a more modern, K8 native scaling solution. The example is updated to show users how to setup Karpenter on clusters created by this module as well as the IAM IRSA module

Breaking Changes

• No

How Has This Been Tested?

• I have updated at least one of the examples/* to demonstrate and validate my change(s)
• I have tested and validated these changes using one or more of the provided examples/* projects

• I have executed pre-commit run -a on my pull request

[antonbabenko]

This PR is included in version 18.20.0 🎉

[archoversight]

aws/karpenter-provider-aws#702 (comment)

This suggests that Karpenter does yet deal with Spot instance termination, so it is not yet a full replacement for NTH.

[github-actions]

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