Fix HPA bug about unintentional scale out during updating deployment.

[shibataka000]

What type of PR is this?

/kind bug

What this PR does / why we need it:

During rolling update with maxSurge: 1 and maxUnavailable: 0, len(metrics) may be greater than currentReplcas and it may cause unintentional scale out in spite of usageRatio and newUsageRatio are less than 1.0. This PR fix that bug.

More detail scenario description and the way to reproduce bug is described in #84142 . Please see it.

Which issue(s) this PR fixes:

Fixes #84142

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

NONE

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

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[k8s-ci-robot]

Hi @shibataka000. Thanks for your PR.

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[neolit123]

/ok-to-test

[shibataka000]

/assign @piosz

[shibataka000]

@piosz Could you review this PR?

[shibataka000]

@piosz @mwielgus Could you review this PR?

[josephburnett]

/lgtm
/approve

@shibataka000 can you apply this fix to calcPlainMetricReplicas as well here:

kubernetes/pkg/controller/podautoscaler/replica_calculator.go

Line 231 in f321d0e

Thank you for this pull request!

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: josephburnett, shibataka000

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[josephburnett]

/test pull-kubernetes-e2e-gce

[shibataka000]

@josephburnett Thank you for your review!

can you apply this fix to calcPlainMetricReplicas as well here:

I did it in #89465 . Could you review it?

[josephburnett]

@shibataka000 sure think, I will review once the automated tests finish.