Add unit tests for Powervs image handling

[Amulyam24]

What this PR does / why we need it:
This PR adds unit tests cases for Powervs image.

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 #581

Special notes for your reviewer:

/area provider/ibmcloud

1. Please confirm that if this PR changes any image versions, then that's the sole change this PR makes.

Release note:

[netlify]

✔️ Deploy Preview for kubernetes-sigs-cluster-api-ibmcloud ready!

🔨 Explore the source changes: 2471606

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😎 Browse the preview: https://deploy-preview-582--kubernetes-sigs-cluster-api-ibmcloud.netlify.app

[k8s-ci-robot]

Hi @Amulyam24. Thanks for your PR.

I'm waiting for a kubernetes-sigs 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.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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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.

[Amulyam24]

/cc @mkumatag

[mkumatag]

/lgtm
/ok-to-test
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Amulyam24, mkumatag

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• OWNERS [mkumatag]

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