Add flag to force remove long unregistered nodes

[BigDarkClown]

What type of PR is this?

/kind feature

What this PR does / why we need it:

Problem:

The Cluster Autoscaler sometimes cannot remove long unregistered nodes. This happens when removing them would leave their node group with fewer than the minimum size required. This wastes resources, as the nodes cannot be used and might be as well deleted.

Solution:

• We've added a new option that lets you forcefully remove these unused machines.
• This option only works if your cloud provider allows deleting machines without checking if it violates the minimum size rule.

Background:

• This effort started with this code change: [WIP] cloudprovider ForceDeleteNodes() used to delete unregistered nodes #6843

Does this PR introduce a user-facing change?

Change adds a flag --force-delete-long-unregistered-nodes, which if used enables the Cluster Autoscaler to remove the long unregistered nodes even if it would break the min size constraints of their node group.

[Shubham82]

Hi @BigDarkClown, the mandatory test case Tests / test-and-verify (pull_request) is failed, Please address it.

Thanks!

[Shubham82]

There are the gofmt and spelling errors, due to which this test case failed.

Run hack/update-gofmt.sh and hack/verify-spelling.sh to fix this issue.

[BigDarkClown]

There are the gofmt and spelling errors, due to which this test case failed.

Run hack/update-gofmt.sh and hack/verify-spelling.sh to fix this issue.

Thanks @Shubham82, I've updated now. Turns out that gofmt picked up a lot of problems in cloudproviders I've modified.

[x13n]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: BigDarkClown, x13n

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