[e2e, scripts] Integrate Teraslice Helm Chart in Kubernetes E2E Testing and k8s-env

[sotojn]

While working on publishing the Teraslice Helm chart, I realized we currently don’t have any tests for it. Our Kubernetes E2E tests manually deploy a Deployment resource using the built Teraslice image, along with custom resources for the other services.

In production, Teraslice is exclusively managed through Helm. Now that the Helm chart is public, we should update our E2E tests to deploy Teraslice using the Helm chart to align with production practices and ensure the chart works as expected.

We should also update k8s-env to use the helm chart as well.