Improve ctrlz_test (#10611)
Improve ctrlz_test (#10611)

* Improve ctrlz_test
- Check for errors
- Use a shorter timeout when waiting for test callback
- Split it as it was two tests

* do

smawson/istio,geeknoid/istio,smawson/istio,geeknoid/istio,istio/istio,smawson/istio,istio/istio,geeknoid/istio,geeknoid/istio,smawson/istio,geeknoid/istio,smawson/istio,geeknoid/istio,istio/istio,istio/istio,smawson/istio,istio/istio