Test removing contrib modules from composer.json

[byrond]

Description

Remove all of the contrib modules from the skeleton since they are installed by The Build.

Testing instructions

1. Create a new project using this branch:
   `composer create-project palantirnet/drupal-skeleton example dev-composer-remove-contrib --no-interaction
2. Verify the desired contrib modules are properly installed.

Remaining tasks

• Revert the addition of the .gitkeep file and create a new release of the build with a step to create the modules/contrib directory during drupal-first-install.
• Revert change to the-build version once Add config_ignore during drupal-first-install the-build#225 is in a release.