temp fix for argo workflow validation error (restore 0.0.7 DAG)

[sbostk]

Fixes

• Restore 0.0.7 workflow DAGs (remove onExit handler and restore "stop" step)
• Add argo workflow lint target to Makefile. Ideally would be run by default against all workflows prior to image build but circleci executor does not have argo cli client installed.

Problem

Release 0.0.8 introduced a functional regression from RS-125/RS-128 for GKE cluster creation.
Release 0.0.8 introduced new AKS support but also included a functional regression from my PR which broke the workflow.
OpenShift and Kops are likely broken as well.

Error reported from Argo Workflow engine

"message": "invalid spec: templates.stop.steps failed to resolve {{steps.create.outputs.parameters.cluster_name}}",

Root Cause

The "onExit" handler I added to Argo workflow definitions worked for "demo" flavor but fails to validate at runtime for other workflows. This PR reverts just the workflows onExit handlers to preserve fixes/enhancements through 0.0.8 but un-break the aberrant workflow handling for cluster flavors other than "demo".

Testing the fix-forward

• demo cluster created
• gke cluster created
• eks cluster created
• aks cluster created (cluster create failures were just resource limit exceedance in Azure)
• calendar scheduled demo created

[gavin-stackrox]

LGTM