Description of problem:
When we have a VM and we start it with API, we can set Initialization type to it.
There are flags such as: useCloudInit, useSysprep, useIgnition that will tell the engine which initialization we wish to use.
But, in case we don't supply this flag we still wish the initialization will pass, and be determined by the OS type.

How reproducible:
100%

Steps to Reproduce:
1. Create a VM.
2. Start the VM wish REST-API(SDK) and set the Initialization in it.

Actual results:
VM doesn't have payload, no initialization in action.

Expected results:
The VM should have the initialization with it.

Additional info:
For example to SDK using ignition(python script):
connection = sdk.Connection(
    url='https://<engine-fqdn>/ovirt-engine/api',
    username=<user>,
    password=<password,
    insecure=True,
    debug=True
)

vms_service = connection.system_service().vms_service()


ignition='''
{
  "ignition": { "version": "3.0.0" },
  "passwd": {
    "users": [
      {
        "name": "core",
        "passwordHash": "$y$j9T$skCa2x5kFis7p58gYjz3C1$ykelHfCckRToZKAVYK7GDdLOCi3pcF2WMioI.vmYkj5"
      }
    ]
  }
}
'''
vm = vms_service.list(search='name=<vm_name>')[0]

vm_service = vms_service.vm_service(vm.id)
vm_service.start(
    vm=types.Vm(
        initialization=types.Initialization(
            custom_script=ignition,
        )
    )
)
connection.close()