Visualization for load generator

## What would you like to be added/changed?

Several scenarios in the workshop benefit from the system being under load, for example:
1. Observability
2. Operational changes that should't cause disruption to "end users" (MNG updates etc)

The sample application includes [artillery](https://github.com/artilleryio/artillery) scenarios to generate load on all of the components. However, it would be useful to be able to visualize statistics coming from artillery to understand when user requests are being impacted by changes.

Initial suggestion is to use existing integration to push metrics from artillery to a Prometheus instance and leverage the existing Grafana to present a dashboard to the workshop user.

https://www.artillery.io/docs/guides/plugins/plugin-publish-metrics#prometheus-pushgateway

This should all be automatically set up in Terraform.