Don't scale down ASGs when placeholder nodes are discovered

[theintz]

What type of PR is this?

/kind bug

What this PR does / why we need it:

Which issue(s) this PR fixes:

Fixes #5829

Special notes for your reviewer:

Does this PR introduce a user-facing change?

[AWS] ASGs are no longer scaled down when there are capacity issues within the ASG

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

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[gjtempleton]

/assign @gjtempleton

[theintz]

We've deployed this patch on our clusters a week ago (patched into v1.26.3) and it appears to have stopped the problems outlined in #5829. Looking forward to your feedback.

[qianlei90]

I'm not familiar with AWS's ASG, but I think one use case should be consider(correct me if I'm wrong)：

If EC2 is out of stock and ASG can not create new instances, CA will delete these nodes after MaxNodeProvisionTime(default 15m). If the desired instance number of ASG is not modified, new instances will still be created and registry to cluster when stock is restored, which is not the expected behavior.

[theintz]

@jaypipes @gjtempleton any feedback?

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/lifecycle stale

[k8s-triage-robot]

The Kubernetes project currently lacks enough active contributors to adequately respond to all PRs.

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/lifecycle rotten

[apy-liu]

/remove-lifecycle rotten