Cloning this bug to the 4.10 version because customer is hitting this problem while upgrading the Openshift Virtualization operator from 4.10.2 to 4.10.9.

Before the upgrade they configure:

```
spec:
  workloadUpdateStrategy:
    workloadUpdateMethods:
    - LiveMigrate
    - Evict
```

When 4.10.9 is installed, workloadUpdateMethods has been overwritten.

Technically the upgrade from 4.10.2 to 4.10.9 should not be strictly considered part of the EUS->EUS upgrade process but just as a preliminary step.
If we want to avoid upgrading migrating/restarting all the VMs to upgrade the virt-launcher image (with qemu and libvirt binaries) knowing that it's going to happen soon once at 4.12, we can still use a workaround there:

An invalid configuration like:
```
spec:
  workloadUpdateStrategy:
    workloadUpdateMethods:
    - None
```
should not cause any side effect with the wrong value being simply ignored, see:
https://github.com/kubevirt/kubevirt/blob/release-0.49/pkg/virt-controller/watch/workload-updater/workload-updater.go#L295-L301

on the other side, having a placeholder value there will be enough to prevent it from getting overwritten with its default configuration.
Looking at the code, the placeholder value can be safely kept in place till the cluster reaches 4.12.