This adds delete_on_termination field for the compute API response schema
for the 2.79 microversion in the following APIs:
- GET /servers/{server_id}/os-volume_attachments (list)
- GET /servers/{server_id}/os-volume_attachments/{volume_id} (show)
- POST /servers/{server_id}/os-volume_attachments (attach)
Change-Id: I7a9b22477b800c6d60acb67c27aff5dcb61d7875