New guidance needed on when and how to remove ComposerScripts

[stevector]

Drupal sites created on Pantheon come with pantheon-upstreams/upstream-configuration

The benefits of this package need more documentation (meant to be used by maintainers of Custom Upstreams) along with reasons to remove it. The pressing reason to remove it is that it seems to interfere with Project Browser.

[greg-1-anderson]

Project Browser is not affected by the upstream configuration subproject. It does object to the use of pantheon-systems/drupal-integrations as a scaffolding extension.

The scaffolding behavior of drupal-integrations has already been removed for new Starshot sites created on Pantheon via the drupal-cms-composer-managed upstream. Create a new Starshot site if you'd like to try the Project Browser. I don't think it has been fully tested yet.

We will also remove scaffolding from new Drupal 10 and 11 sites in the future, followed by an eventual removal on all sites via the pre-update hook in our ComposerScripts. i.e. once we do this, the scaffolding behavior will be removed from sites once they do an upstream update. The only thing holding us back from doing this is testing.

Scaffolding can be removed right now from any existing site following the instructions in the drupal-integrations README

[stevector]

@greg-1-anderson, speaking of instructions in drupal-integrations, can you review/merge pantheon-systems/drupal-integrations#39?