Merge pull request #63870 from shyamjvs/autocalculate-allowed-not-ready-nodes

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
```

test/e2e/framework/test_context.go

@@ -374,4 +374,8 @@ func AfterReadingAllFlags(t *TestContextType) {
 			t.Host = defaultHost
 		}
 	}
+	// Allow 1% of nodes to be unready (statistically) - relevant for large clusters.
+	if t.AllowedNotReadyNodes == 0 {
+		t.AllowedNotReadyNodes = t.CloudConfig.NumNodes / 100
+	}
 }