Description of problem:
If a VM template has any parameter that is required but does not provide a default value, the storage disk source is lost.

Version-Release number of selected component (if applicable):
Openshift 4.12.0
Openshift Virtualization 4.12.0

How reproducible:
Always

Steps to Reproduce:
1. Create a VM template with a required parameter and no default value, for example:

~~~
parameters:

• description: SSH pubkey for the cloud-init user
  name: CLOUD_USER_SSH_KEY
  required: true
  ~~~

2. In the console, go to Virtual Machines -> Create from catalog -> Select template -> Customize Virtual Machine.

Actual results:
CLOUD_USER_SSH_KEY is empty and required as expected, however in Storage -> Disk source, the details of the source storage has been lost.

Expected results:
I expect that "Template default" is selected in Storage -> Disk source.

Additional info: