linux-builder: Add ephemeral option to delete VM's disk image on service restart
#1213
| Job | Run time |
|---|---|
| 3m 19s | |
| 3m 55s | |
| 2m 53s | |
| 2m 47s | |
| 6m 15s | |
| 10m 33s | |
| 29m 42s |