Update dev-environment.yaml and remove test_helm.py

[consideRatio]

I wanted to avoid the duplication of python dependencies, and dev-environment.yaml was the last place there was duplication.

I'm also opining to remove the built in helm lint and helm install --dry-run tests that can run locally for a combination of reasons.

• I ran into errors running them locally because of they require that you don't have various credentials helpers for working with a k8s cluster, and that your default kubernetes config isn't causing trouble etc.
• It requires helm and makes us need to install it for a local dev setup.
• It is already tested in github workflows testing the helm chart more thoroughly

Closes #546.