Fix panic when processing http response

[feiskyer]

What this PR does / why we need it:

When Azure ARM API gets something wrong, kube-controller-manager may panic because of azure cloud provider:

/usr/local/go/src/runtime/asm_amd64.s:2361
panic: runtime error: invalid memory address or nil pointer dereference [recovered]
	panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x1d4cad9]

goroutine 1386 [running]:
k8s.io/kubernetes/vendor/k8s.io/apimachinery/pkg/util/runtime.HandleCrash(0x0, 0x0, 0x0)
	/go/src/k8s.io/kubernetes/_output/dockerized/go/src/k8s.io/kubernetes/vendor/k8s.io/apimachinery/pkg/util/runtime/runtime.go:58 +0x107
panic(0x44468c0, 0x8b76a30)
	/usr/local/go/src/runtime/panic.go:502 +0x229
k8s.io/kubernetes/pkg/cloudprovider/providers/azure.processHTTPRetryResponse(0x0, 0x64ffec0, 0xc4229fd1f0, 0xc422ed05b0, 0x2, 0x2)
	/go/src/k8s.io/kubernetes/_output/dockerized/go/src/k8s.io/kubernetes/pkg/cloudprovider/providers/azure/azure_backoff.go:364 +0x69
k8s.io/kubernetes/pkg/cloudprovider/providers/azure.(*Cloud).CreateOrUpdatePIPWithRetry.func1(0xc422ed0600, 0x0, 0x0)
	/go/src/k8s.io/kubernetes/_output/dockerized/go/src/k8s.io/kubernetes/pkg/cloudprovider/providers/azure/azure_backoff.go:205 +0x298

This PR fixes that.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #68209

Special notes for your reviewer:

Should cherry pick to old releases.

Release note:

Fix panic when processing Azure HTTP response.

[feiskyer]

/sig azure
/kind bug
/milestone v1.12

[feiskyer]

/assign @andyzhangx

[andyzhangx]

/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: andyzhangx, feiskyer

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Needs approval from an approver in each of these files:

• pkg/cloudprovider/providers/azure/OWNERS [andyzhangx,feiskyer]

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[feiskyer]

/retest

[k8s-github-robot]

Automatic merge from submit-queue (batch tested with PRs 67986, 68210, 67817). If you want to cherry-pick this change to another branch, please follow the instructions here: https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md.