fix: azure_loadbalancer.go: don't use service.Name, when service is nil

[damdo]

What type of PR is this?

/kind bug

What this PR does / why we need it:

Summary:
The service object is always nil when code execution reaches this line and as such, logging service.Name will result in a nil pointer dereference panic (see this panic log (note that this comes from an older fork, so panic code lines might not exactly match)).

Analysis:
If if !serviceExists is satisfied, we log a line with service.Name
But for the execution to branch into if !serviceExists, serviceExists must be false.
Looking at getLatestService where service and serviceExists come from, you’ll see that the only case when serviceExists is false, service is nil, resulting in a nil pointer dereference panic.
Changing to serviceName (a pre populated string) instead of service.Name should fix this issue.

Does this PR introduce a user-facing change?

fix: azure_loadbalancer.go: don't use service.Name, when service is nil

[damdo]

/assign @feiskyer @nilo19 @MartinForReal

[nilo19]

/lgtm

[nilo19]

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: damdo, nilo19

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[nilo19]

/cherrypick release-1.28

[k8s-infra-cherrypick-robot]

@nilo19: new pull request created: #5269

In response to this:

/cherrypick release-1.28

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[nilo19]

/cherrypick release-1.27

[nilo19]

/cherrypick release-1.26

[nilo19]

/cherrypick release-1.25

[k8s-infra-cherrypick-robot]

@nilo19: new pull request created: #5273

In response to this:

/cherrypick release-1.27

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[k8s-infra-cherrypick-robot]

@nilo19: new pull request created: #5274

In response to this:

/cherrypick release-1.26

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[k8s-infra-cherrypick-robot]

@nilo19: new pull request created: #5275

In response to this:

/cherrypick release-1.25

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.