Don't fetch nodegroup info from cloud provider if node is in scaledown

[tetianakh]

What type of PR is this?

/kind bug

What this PR does / why we need it:

If a node is being scaled down, it may get deleted at any time. Currently during large scaledowns cluster autoscaler is unable to associate nodes that are being deleted nodes with a nodegroup, causing expensive cache updates.
This change checks if a node is in scaledown and gets the nodegoup from scaledown request, not from cloud provider.

It also increases the MaxKubernetesEmptyNodeDeletionTime and MaxCloudProviderNodeDeletionTime to account for tail latencies in large bulk deletes.

Special notes for your reviewer:

Does this PR introduce a user-facing change?

NONE

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[x13n]

The description mentions bumping MaxCloudProviderNodeDeletionTime and MaxKubernetesEmptyNodeDeletionTime, but I don't see that change in the code. Is it a separate commit that you meant to push?

Also, can you update the release note? I think this is a performance optimization that may be worth calling out in the changelog.

[elmiko]

++ to @x13n 's question.

[tetianakh]

Thanks for noticing, changes in cluster-autoscaler/core/scaledown/actuation/delete_in_batch.go are missing from the commit.

Let me take another try at fixing this. After running more thorough tests I am less confident that this change fully fixes the problem.