✨(frontend) create generic theme

By default Docs will not be on the dsfr theme but
on the generic theme. La Gaufre is part of the dsfr
theme and is removed from the generic theme.
Same for the "beta" keyword and the "proconnect"
buttons.

env.d/development/common.dist

@@ -61,6 +61,3 @@ COLLABORATION_BACKEND_BASE_URL=http://app-dev:8000
 COLLABORATION_SERVER_ORIGIN=http://localhost:3000
 COLLABORATION_SERVER_SECRET=my-secret
 COLLABORATION_WS_URL=ws://localhost:4444/collaboration/ws/
-
-# Frontend
-FRONTEND_THEME=default