chore(ci): simplify github actions execution

[squakez]

This PR is an heavy refactoring of the E2E. It reduces duplication and aim to have a simpler maintenance, robustness and execution speed. I've worked to make them executing in parallel with the presence of a global operator. Only the advanced tests are in charge to install their own operator as they are meant to work with certain particular conditions (ie, changing the behavior of the platform or the same operator).

Missing tasks:

• [x] Deprecate kamel install once tests are passing
• [ ] Fine tune test parallelism

Closes #5615

Release Note

chore(ci): simplify github actions execution