feat: CPU startup boost in master

[kamarabbas99]

What type of PR is this?

/kind feature
/kind api-change

What this PR does / why we need it:

The CPU startup boost chnges were done on experimental branch, moving this to master.

Special notes for your reviewer:

Does this PR introduce a user-facing change?

Users can configure a startupBoost policy in the VPA spec. 

Which issue(s) this PR fixes:

#7862

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

- [KEP]: (https://github.com/kubernetes/autoscaler/tree/master/vertical-pod-autoscaler/enhancements/7862-cpu-startup-boost#aep-7862-cpu-startup-boost)

[kamarabbas99]

/cc adrianmoisey omerap12

[k8s-triage-robot]

This PR may require API review.

If so, when the changes are ready, complete the pre-review checklist and request an API review.

Status of requested reviews is tracked in the API Review project.

[omerap12]

Nice! we already approved this in previous PRs 🥳
/lgtm
/label tide/merge-method-squash

[omerap12]

oh good catch
/lgtm cancel

[adrianmoisey]

/cc @soltysh
Do you mind doing API review on this?
It was previously reviewed over in #8417, when it was merged into a feature branch.
But now that we're merging it into master, I assume it needs re-review?

[adrianmoisey]

I'm good with this, thanks for doing it!
/lgtm

[omerap12]

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: kamarabbas99, omerap12
Once this PR has been reviewed and has the lgtm label, please assign liggitt for approval. For more information see the Code Review Process.

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• vertical-pod-autoscaler/OWNERS [omerap12]
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