[EMS-22255] Add disk_controller_type support to virtual_machine_default

[lyudmililchev92]

Summary

Allows switching the disk controller (SCSI ↔ NVMe) of VMs managed by the default type (azurerm_virtual_machine). This is required to resize existing VMs to NVMe-only sizes such as Easv6.

azurerm_virtual_machine is feature-frozen in the AzureRM provider and has no disk_controller_type argument. Azure only allows changing the controller in the same request as a size change.

Changes

• New optional setting disk_controller_type ("NVMe" / "SCSI") for type = "default" VMs.
• When set, azapi_update_resource sends vmSize + diskControllerType in one request.
• azurerm_virtual_machine.main now depends_on that resource, so the azapi update runs first. The azurerm update that follows only applies the size that is already set.
• No change for existing configurations: without disk_controller_type the azapi resource has count = 0.

Usage

vm_example = {
  type                 = "default"
  size                 = "Standard_E4as_v6"
  disk_controller_type = "NVMe"
  ...
}

Notes

• Existing VMs only. The resource ID is built from the name because of the depends_on, so on create the azapi update would run before the VM exists. For new VMs Azure picks the controller from the size, so the setting is not needed.
• Guest OS prerequisite for SCSI → NVMe: the NVMe driver (stornvme) must be set to boot start in Windows before applying. Otherwise the VM will not boot.
• Not yet tested against a real VM. The first use will be the pilot on the ASV test Colibri VMs (dca-test-col-app, dca-test-col-db), with a terraform plan review before apply.

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