Remove the `drupal_` prefix from all recipes

Looks like we can't do this unless we can also take over the cms_events project namespace. That project is abandoned so I imagine it won't be a problem, but it's a hard blocker to doing this.

Ultimately we have decided not to do this.

There are some branding issues about it, some infrastructure blockers, and although we don't dislike this idea, it's not important enough to pursue. We have bigger fish to fry.