chore: backport latest VMs pool and HasInstance() implementations, for 1.30

[comtalyst]

What type of PR is this?

/kind cleanup

What this PR does / why we need it:

These differences have effectively disabled cherry-pick automation in these areas. Upcoming changes (e.g., more VMs pool implementation, cloud-provider-azure integration rework, more fixes that need to be done in all versions) will be agonizing experiences, not to mention the past ones.
This PR will amend some of those differences, which is mostly VMs pool and HasInstance() implementations. They cannot be cherry-picked in normal means easily due to conflict with Azure defork operations, which have to resolve these conflicts at some point anyway.

Which issue(s) this PR fixes:

• [BUG] Cluster autoscaler bug requires Azure specific implementation to resolve Azure/AKS#4286
• CA fails to scale-up or cancel in-progress scale down when there are un-schedulable pods  #4456

Special notes for your reviewer:

Original HasInstance() implementation PR: #6956
Differences visualization I used as a reference, with some labels: https://github.com/comtalyst/autoscaler/pull/3/files

Does this PR introduce a user-facing change?

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

[comtalyst]

/label tide/merge-method-squash

[k8s-ci-robot]

@comtalyst: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-cluster-autoscaler-e2e-azure	ab058dc	link	false	/test pull-cluster-autoscaler-e2e-azure

Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

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[comtalyst]

/assign @towca

[tallaxes]

/lgtm

[towca]

Could you remove the vendor changes from the PR? We've removed the vendor dir from CA altogether, see #4878.

[comtalyst]

@towca I thought that is effective beginning 1.31 (master). Still seeing #7046 and similar.
Also, test-and-verify didn't pass after removing vendor changes.

[towca]

Ahh my bad, indeed vendor is still there on 1.30. Sorry for the confusion.

/approve
/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: comtalyst, tallaxes, towca

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