[QE] Review e2e image

[adrianriobo]

We need to review the current e2e image to adapt it to the common stack used across qe:

• [x] Inherit from deliverest https://github.com/adrianriobo/deliverest/
• [x] Add the tkn spec within the project
• [x] Added recently added memory param to customize the base memory for running tests
• [ ] Added metrics

[adrianriobo]

For metrics we can not set them up from the outside, we need to add a flag within the e2e which enables them;

Once cluster has been started, ssh into machine and:

kubectl --kubeconfig /opt/kubeconfig proxy --port 52200 &
curl gateway.containers.internal/services/forwarder/expose -X POST -d '{"127.0.01":":52500","remote":"192.168.127.2:52200"}'

Now we can use from host curl http://localhost:52200/metrics and got prometheus metrics on the cluster

Some visualization idea: https://grafana.com/grafana/dashboards/3870-openshift-k8-cluster-overview/