Drop drupal as an app that can be installed via the control panel
I think we should stop offering to install drupal via the web app control panel.
When I added support for drupal9, it was still possible to upgrade drupal9 via drush, but now that is deprecated. Furthermore, the complicated drush with drupal compatability means that we will never have the right version of drush installed. Drupal really expects each site to install their own drush to avoid this mess.
Currently, we install drupal by downloading a zip file. This installation method will probably continue to be possible, but composer is the recommended way to do it.
We could upgrade drupal by simply downloading the new zip file and rsycing it over (that's how backdrop is upgraded). However, I think Drupal is not the right tool for someone who is not prepared to use composer and manage it in the intended way. And, I'm worried that we will not be able to keep up with new features in Drupal.
Right now there are nine active drupal9 apps, including one of Jaime's test apps. If we drop Drupal, we should probably tell them they will have to manage upgrades from now on.
@jaimev Let me know what you think.