The test connection pod cannot be disabled or changed

[uhthomas]

This is a major problem for many reasons:

• The templates cannot be rendered and applied with kubectl.
• The container image is always busybox from Docker Hub, with no ability to pin or change it.
• The templates cannot be applied in clusters which have strict registry enforcement (i.e cannot pull from Dockerhub).

Can this be removed or optionally disabled?

https://github.com/sourcegraph/deploy-sourcegraph-helm/blob/45e9b384b00ba9a35124448e8ad071c354682922/charts/sourcegraph/templates/tests/test-connection.yaml