EKS [request]: managed nodegroup cloudwatch integration

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**Tell us about your request**
What do you want us to build?

**Which service(s) is this request for?**
EKS

**Tell us about the problem you're trying to solve. What are you trying to do, and why is it hard?**

Updating a managed node group should send logs to cloudwatch so customer is aware the current state of update/upgrade. logs should capture actions taken by managed node group in update process and also report errors if update/upgrade fails for any reason.

Further in case of managed node group update/upgrade failure customer should have a cloudwatch metric that teams could use to notify their oncalls.

**Are you currently working around this issue?**
NA

**Additional context**
NA

The issue names EKS managed node group updates and CloudWatch, but no repository files, tests, or entry points. Start by reviewing the EKS managed node group update flow and CloudWatch integration requirements; done would include update logs and a failure metric suitable for on-call notifications.

Written by the indexing model from the issue text.