Unable to Deploy Spoke without Management VM

[ludoll-uwm]

With the following parameter:
param researchVmsAreSessionHosts = true ;
We are able to get through the Hub deployment.

We are experiencing failures where it seems the research VMs are relying on the presence of a Hub Management VM that does not exist.
(Referenced in the main.bicep file for the Spoke)

// TODO: Split once into var and re-use var
var hubManagementVmSubscriptionId = split(hubManagementVmId, '/')[2]
var hubManagementVmResourceGroupName = split(hubManagementVmId, '/')[4]
var hubManagementVmName = split(hubManagementVmId, '/')[8]

Error Received:

Line |
83 | $DeploymentResult = New-AzDeployment @CmdLetParameters
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| 11:52:12 AM - Error: Code=InvalidTemplate; Message=Deployment template validation failed: 'The template variable 'hubManagementVmSubscriptionId' is not valid: The language expression property array index '2' is out of bounds.
Please see https://aka.ms/arm-functions for usage details.'.

[SvenAelterman]

Spoke deployment assumes there will always be a parseable resource ID for the management VM, even if AD join is not necessary.

(unconfirmed) Moreover, the storage account module may require the resource group for the management VM to existing in the hub subscription even if it's not needed.

• Do not try to parse empty value.
• When logonType in spoke is entraID, then filesIdentityType should default to AADKERB
• Validate that when no AD domain join for the storage account is attempted, the management RG in hub sub does not need to exist.