ci-base has become very bloated #273
Description
In 767e8f9 a lot of additional tooling was added to the base docker image.
My assumption was that the base image represented the essential tooling needed to build a Zephyr application under CI. In other words, the base image would be sufficient to use for "getting started".
Previously I was able to use the base for producing my own CI images that were a "controlled environment" that provided the correct matching SDK tooling. Now the base image is "bloated" with many more installations (sparse, llvm, renode, etc).
Would it be possible to reconsider this split or introduce a new 4th layer to the equation, one that essentially satisfies the "getting started" guide requirements of the base system.