Description of problem:
After doing a EUS-to-EUS upgrade from 4.10 to 4.12, all customized VM templates are marked as deprecated and have to be manually modified to be usable.

Version-Release number of selected component (if applicable):
4.12

How reproducible:
Always

Steps to Reproduce:
1. In 4.10 create a custom VM template. See below some details of the template that we had to modify after the upgrade:

```
metadata:
  labels:
    app.kubernetes.io/version: 4.12.4
    template.kubevirt.io/version: v0.19.4
    template.kubevirt.io/type: base
objects:
- apiVersion: kubevirt.io/v1
  kind: VirtualMachine
  metadata:
    labels:
      app: ${NAME}
      vm.kubevirt.io/template: rhel8-server-small
      vm.kubevirt.io/template.revision: "1"
      vm.kubevirt.io/template.version: v0.19.4
    name: ${NAME}
  spec:
    template:
      metadata:
        annotations:
          vm.kubevirt.io/flavor: small
          vm.kubevirt.io/os: rhel8
          vm.kubevirt.io/workload: server
        labels:
          kubevirt.io/domain: ${NAME}
          kubevirt.io/size: small
      spec:
        domain:
          machine:
            type: pc-q35-rhel8.4.0
parameters:
- description: Name for the new VM
  name: NAME
  required: true
```

2. Upgrade to 4.12

Actual results:
Templates are marked as deprecated and manual modifications are needed.

Expected results:
No manual intervention after the upgrade. The custom template should upgrade automatically.

Additional info:
Some of the changes needed have been documented in this solution:
https://access.redhat.com/solutions/7030930