Revert "Moving to CircleCI 2.1 (#8923)" (#8937)
Revert "Moving to CircleCI 2.1 (#8923)" (#8937)

This reverts commit 8d9c38c8c42b984551db0ba90076a97d1aabe051.
istio/istio,geeknoid/istio,geeknoid/istio,smawson/istio,geeknoid/istio,smawson/istio,istio/istio,geeknoid/istio,smawson/istio,istio/istio,smawson/istio,smawson/istio,geeknoid/istio,istio/istio,geeknoid/istio,istio/istio,smawson/istio