GCP - Add exception for onHostMaintenance Migrate on confidential compute n2d instances

[WTFKr0]

This PR closes #1405

Context

Provisionning Machines on GCP Provider
With confidential compute enabled
Try to set onHostMaintenance to Migrate

Current Issue

Today the webhook refused this case, as it is forbidden by default on GCP.

But an exception exists on n2d series
See this doc for information : https://cloud.google.com/confidential-computing/confidential-vm/docs/troubleshoot-live-migration

Resolution

Add an exception on the webhhook for the n2d series VM, and accept the Migrate onHostMaintenance

Environment

This issue is present on Openshift 4.16, 4.18 and 4.19 for sure

[openshift-ci]

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[openshift-ci]

Hi @WTFKr0. Thanks for your PR.

I'm waiting for a openshift 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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