vdaf: Isolate prio_draft09 usage as much as possible
#2811
| Job | Run time |
|---|---|
| 7m 48s | |
| 5m 52s | |
| 13m 40s |
prio_draft09 usage as much as possible
#2811
| Job | Run time |
|---|---|
| 7m 48s | |
| 5m 52s | |
| 13m 40s |