If a storage account type is not entered when creating a shared unmanaged disk storage class on Azure Disk, the PV will fail to create. This occurs on k8s versions >= 1.12

To reproduce:

• Deploy Rancher v2.2.4-rc5
• Create Azure cluster w/ cloud provider, k8s version >= 1.12
• Create a storage class for Azure Disk - shared unmanaged, without specifying the storage type
• Create workload with a new volume from the storage class
• The workload and PV will fail to create.

• If the storage account type is specified, the PV will create regardless of k8s version.
• This does not occur on k8s v1.11.
• This does not occur with the dedicated unmanaged disk.
• This does not seem to be dependent on Rancher version:
  • Created a v1.11 cluster in v2.1.7 without storage account type set
  • PV provisioned after upgrade (before upgrading k8s version)
• This occurs in other versions of Rancher where clusters are created with k8s v1.12+ (v2.1.7, v2.2.2, etc..)
• This occurs in clusters that have been upgraded beyond k8s v1.11 (if a storage class was working in a v1.11 cluster, new volumes will fail to provision after the cluster is upgraded)