Automated cherry pick of #121015: Add nil checks for hpa object target type values

[Lukasz-AWS]

Cherry pick of #121015 on release-1.27.

#121015: Add nil checks for hpa object target type values

For details on the cherry pick process, see the cherry pick requests page.

What type of PR is this?

/kind bug

What this PR does / why we need it:

Fixes a bug where if the corresponding value (value, averageValue) of the the type of target (Value, AverageValue) is not set but the opposite type is, HPA object would pass validation but then cause kube-controller-manager to crash loop due to nil pointer dereference looking for that corresponding value. This PR adds a nil check to make sure kube-controller-manager doesn't crash. The change to fix the validation is being worked on here #120373

Which issue(s) this PR fixes:

N/A
Fixes #

Special notes for your reviewer:

Observed in 1.27 and 1.28.
Can be replicated by deploying an hpa with a valid scaleTargetRef and adding this object to the metrics. On sync kcm will crash due to nil pointer dereference.

...
- apiVersion: autoscaling/v2
  kind: HorizontalPodAutoscaler
  spec:
    maxReplicas: 10
    metrics:
    - type: Object
      object:
        metric:
          name: requests-per-second
        describedObject:
          apiVersion: networking.k8s.io/v1beta1
          kind: Ingress
          name: main-route
        target:
          type: AverageValue
          value: 1
...

Does this PR introduce a user-facing change?

NONE

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

[k8s-ci-robot]

This issue is currently awaiting triage.

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[k8s-ci-robot]

Hi @Lukasz-AWS. Thanks for your PR.

I'm waiting for a kubernetes member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[Lukasz-AWS]

/kind bug

[liggitt]

/ok-to-test
/lgtm
/approve

[k8s-ci-robot]

LGTM label has been added.

Git tree hash: 927b18224f34a041470540ce2e0ee7cd427999f4

[liggitt]

cc @kubernetes/release-managers

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: liggitt, Lukasz-AWS, saschagrunert

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• pkg/controller/podautoscaler/OWNERS [liggitt]

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