Use admissionregistration.k8s.io/v1beta1 to be k8s < 1.16 compatible

[aledbf]

What this PR does / why we need it:

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Which issue/s this PR fixes

fixes #5769

How Has This Been Tested?

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I've read the CONTRIBUTION guide
• I have added tests to cover my changes.
• All new and existing tests passed.

[ChiefAlexander]

/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: aledbf, ChiefAlexander

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[ChiefAlexander]

As discussed in our slack conversation I think that we should define what we at a minimum support for this chart for Kubernetes versions. And then for these versions of APIs that change provide a default for the versions with the ability to overwrite them via our vars.

[aledbf]

/retest