Fixes #35062 - avoid data contamination in field validation

[lfu]

Changed the way to set up the invalid fields when a hypervisor_type is selected.

To test
1 Create a virt-who config for a non-Nutanix type, eg. Container-native virtualization
2 Create a Nutanix virt-who config
This would fail without fix with error Prism flavor Invalid option for hypervisor [ahv].
Then apply the fix and repeat the steps. All configs should be created without issues.

[chris1984]

ACK, Works well I tried multiple configs and did not hit the error, where i did before applying the patch. Nice work @lfu