Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.
Auto-calculate allowed-not-ready-nodes in test framework
Actually we (sig-scalability) are pretty much the only users of this flag.
This reduces the overhead of having to provide its value based on num-nodes each time we run our tests.
/cc @wojtek-t
```release-note
NONE
```
8c240523ca