[META] Plan next "major" iteration of the GitLab templates

Problem/Motivation

These templates were created and made available to all contrib in summer 2023. The current usage is at +3k (this is GitLab CI usage, not just these templates, but the vast majority of that number is this templates).

There are some design problems/issues that have been dragging along since the beginning, which are hard to solve keeping backwards compatibility and there are also feature requests or big optimisations that can be done and have been suggested.

We have tagged with "2.x" some of those issues, but if we are to do a big refactoring exercise, we need to plan it first and think about other parts of this, like the release strategy, the versions, the use of GitLab components or features, etc.

The tagged issues can be seen in this link → .