tools: mock some Python utils in v8.nix to reuse builds
#7085
| Job | Run time |
|---|---|
| 1m 11s | |
| 1h 4m 49s | |
| 1h 59m 7s | |
| 2h 1m 33s | |
| 3h 39m 11s | |
| 21m 17s | |
| 22m 5s | |
| 22m 12s | |
| 21m 32s | |
| 22m 1s | |
| 21m 47s | |
| 10h 56m 45s |