Set up E2E tests on new release candidate

[nandiheath]

Is your feature request related to a problem? Please describe. For releasing a new release (a new version of a helm chart), we didn't test and guarantee there are no obvious/blocking bugs.

Describe the solution you'd like We should have an automated e2e tests that spin a new k8s cluster and install KintoHub on it, and test deploying all major types of services to guarantee they all work fine.

This would be complex and also resource-intensive but I would put it onto the list first to make sure our future developments are testable/test-oriented.