get rid of balena base image for containers

[pritamghanghas]

we currently use balena base image for our containers. We are not using any of their features as AFAIK. But the latest python in it creates problems with pip and some very large package fall back to compilation like grpc and gobject.

Acceptance Criterion

• switch to a debian lite base image instead of nebra image.
• use github registry for cache rather than docker.

[shawaj]

The only feature we use is install_packages feature and the supervisor labels but apart from that I don't think anything