Make tiny model creation + pipeline testing more robust
(After this, we/I can start to look the current skipped failing pipeline tests. I will also start to write the documentation on how some CIs are performed on Notion)

# What does this PR do?

- make pipeline testing **could also** work against **local** tiny models
- make tiny model creation script work with multi-processes
- A (renamed) workflow to:
  - (new steps) create **all** tiny models locally + run pipeline tests against local tiny models
  - (steps already on `main`) create + upload tiny models for new model **architecture** to Hub and generate new summary file

### Motivation
- make sure any modification to the tiny model creation script don't break things
- to ease the process of updating the summary file and test new tiny models on Hub)
_The documentation is not available anymore as the PR was closed or merged._