refactor(@vtmn/assets): delete scripts and prepare for welcoming assets handoff automation

[lauthieb]

Changes description

Delete scripts and prepare for welcoming assets handoff automation. Needs to be merged before: https://github.com/Decathlon/vitamin-design/pull/212

Checklist

• [x] Make sure you are requesting to pull a topic/feature/bugfix branch. Please, don't request directly from your main!
• [x] Check commits & PR names matches our requested structure. It must follow the https://www.conventionalcommits.org pattern.
• [x] Check your code additions will fail neither code linting checks.
• [x] I have reviewed the submitted code.
• [x] I have tested on related showcases.
• [x] If it includes design changes, please ask for a review design-system-core-team-design GitHub team.

Does this introduce a breaking change?

• No