CI/UX: unify the commands used, and provide a reproducible testing environment

[dannywillems]

The developer should be able to reproduce the exact same behavior of the CI on their machine.
Even though act can be used to reproduce the CI environment, it has an overhead of setting up the whole set of dependencies the CI would need to run the actual command the developer wants.

We propose to improve the existing Makefile and use the target in the CI.
We started to do so in #1172 for instance.