Build the bugbuster image using a distroless approach

[endersonmaia]

It's good practice for the container ecosystem to have minimal (distroless) images with a reduced attack surface and smaller storage and transfer footprint.

Considering the security aspect of bug-buster, reducing the attack surface is a good objective.

Sugestion

Since we're using Ubuntu as a base image, we could leverage Canonical's chisel tool.

[claudioantonio]

@endersonmaia link for chisel on the description is broken.

[guidanoli]

@endersonmaia link for chisel on the description is broken.

Fixed it. :-)