helm e2e tests for our plugins installed via helm+plugin manager.

We should have e2e tests for helm installs. We also need helm e2e tests for our plugins installed via helm+plugin manager.

The goals are:

• make sure helm chart is e2e tested
• make sure plugin manager used with helm is tested (plugins installed in-cluster)
• make sure headlamp changes on main branch integrates with released plugins from artifact hub