Allow the usage of Ephemeral OS Disk with multiple VM SKUs

[naioja]

Is your feature request related to a problem? Please describe.
I would like to use VM SKUs as AKS nodepools that support Ephemeral Disk but the cache size is not larger than 130GiB.
One example would be the VM SKU Standard_DS2_v2 that has 86 GiB and documented here : https://learn.microsoft.com/en-us/azure/aks/cluster-configuration#ephemeral-os

Describe the solution you'd like
The ability to use a broader less expensive VM SKU variety that have over 30 GiB of cache storage.

[github-actions]

Issue smells stale, no activity for 30 days. Stale Label will be removed if the issue is updated, otherwise closed in a month.

[Gordonby]

With ephemeral OS you can deploy VM and instance images up to the size of the VM cache. In the AKS case, the default node OS disk configuration uses 128 GB, which means that you need a VM size that has a cache larger than 128 GB. The default Standard_DS2_v2 has a cache size of 86 GB, which isn't large enough. The Standard_DS3_v2 has a cache size of 172 GB, which is large enough. You can also reduce the default size of the OS disk by using --node-osdisk-size. The minimum size for AKS images is 30 GB.

Linked to #608 and #609

Tagging @khowling for visibility.