[Bug] Existing machines in a catalog does not have their ProvVm vmTemplate updated

[nicoBruhn]

Describe the bug

In a citrix_machine_catalog when updating the provisioning_scheme.azure_machine_config.machine_profile with a new template_spec_version the existing provisioned machines will not get their ProvVm updated with the newest template spec. Instead the ProvVm for the old machines in the catalog will keep their copy of the old template spec.

Only machines added after the template spec changes will have the newest version of the template applied. Currently, we will have to scale the machines down in the catalog to 0 and rerun terraform apply with new the machine account in order to apply the template spec changes. This you cannot e.g. add extra data collection rules, application security groups etc. to existing machines.

Steps to reproduce:

1. Create a Machine catalog with in Azure with a template spec as the machine profile.
2. Update the template spec to a new version and update the machine catalog.
3. Add a new machine. Use the Citrix powershell module and notice that when calling
   Get-ProvVm -ProvisioningSchemeUid "XXXXXX" that in the section CustomVmData.VmTemplate that the template changes is only applied to the newly added machine.

Versions

Terraform: 1.14.3
citrix/citrix provider: 1.0.31
Operation system: Linux

Environment type: Cloud
Hypervisor type (if applicable): Azure

Terraform configuration files

N/A

Terraform console output

N/A

Terraform log file

N/A

[aneeshk-citrix]

@nicoBruhn I don't think prov scheme updates are applied to existing machines by default. This is the actual behavior in DaaS and not a terraform provider issue. Have you tried the APIs directly and noticed a different behavior?

We've had requests in the past for adding functionality to update existing machines when prov scheme is updated. Refer to #270. We introduced a new property on the machine catalog called apply_updates_to_existing_machines https://registry.terraform.io/providers/citrix/citrix/latest/docs/resources/machine_catalog#apply_updates_to_existing_machines-1 for this use case.