Goal: 
In import_workload_transfer_volumes.py, we assume /dev/vda is a boot volume and not used for data volume.
It is based on a strong assumption that /dev/vda is boot volume and it doesn't relate to data for application in instance. There is a case that a tenant user may save application data in the single volume, boot volume.
We should make delete_on_termination option editable for making it false to boot volume.

https://github.com/os-migrate/os-migrate/blob/main/plugins/modules/import_workload_transfer_volumes.py#L424-L452
 
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https://github.com/os-migrate/os-migrate/issues/729

Acceptance Criteria:

A list of verification conditions, successful functional tests, or expected outcomes in order to declare this story/task successfully completed.

• Verify X
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