Add preAutoloadDump script

[webflo]

Lets add https://www.drupal.org/node/2764267 to the composer.json by default once its fixed in core.

[andypost]

The same time makes sense to adopt vendor tests clean-up #323

[leymannx]

@webflo – Is this still active/relevant? I don't understand what needs to done for this issue. Can you maybe open a PR? 🙂

[AlexSkrypnyk]

This pull request/issue has been inactive for over a year and is being closed due to inactivity. If the issue still persists or the contribution is still relevant, please feel free to reopen it or create a new one.

Thank you for your understanding and your contributions to the project!