Update images and handle the Buster ELTS and Bullseye LTS switch
This MR has three parts/goals:
- Remove the duplicated images that we can used from the upstream pipeline (the Salsa CI Team's pipeline). These images concern mainly the bullseye and sid images. There is no need to build them and keep them in the LTS Team's container registry.
- Handle bullseye as LTS release. Relying on the Salsa CI Team's registry to pull the bullseye images from, handling bullseye as LTS means adding recipe and test pipeline
- Handling buster as ELTS release
This MR supersedes !22 (closed).
Edited by Santiago R.R.