OCM-3909: Fix availability zones to ListNull in case nothing returned

[nirarg]

In case the user doesn't provide the availability zone, cluster create returnes before it ready and with empty azs list.
This change is done in order to avoid from the following error:

[openshift-ci-robot]

@nirarg: This pull request references OCM-3909 which is a valid jira issue.

Warning: The referenced jira issue has an invalid target version for the target branch this PR targets: expected the bug to target the "4.15.0" version, but no target version was set.

In response to this:

In case the user doesn't provide the availability zone, cluster create returnes before it ready and with empty azs list.
This change is done in order to avoid from the following error:

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.

[nirarg]

/cc @JohnStrunk

[JohnStrunk]

/lgtm

[nirarg]

/retest

[sagidayan]

/approve

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: JohnStrunk, sagidayan

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