fix: validation of caching options for Ultra disks as data disks

[damdo]

What type of PR is this?
/kind bug

What this PR does / why we need it:
Fixes a validation bug for Ultra disks as data disks.

Which issue(s) this PR fixes:
Fixes #2429

TODOs:

• squashed commits
• includes documentation
• adds unit tests

Release note:

Fix cachingType validation for Ultra disks as data disks

[k8s-ci-robot]

Hi @damdo. Thanks for your PR.

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[damdo]

I've now rebased this on top of the latest main as there were conflicts after the #2421 merge.

cc. @jackfrancis

[jackfrancis]

@damdo this looks great, just one comment about UT

thank you so much!

[jackfrancis]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: jackfrancis

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[jackfrancis]

/ok-to-test

[damdo]

/retest