[schema2sql] Drop most of the DB DROP related code
This code is dead for a while, it has been superseded by
`sql_drop_all_user_tables`.
Related to #14050899
Document: cubicweb-doc
Title: CubicWeb documentation
Author: Logilab
Abstract: Some base documentation for CubicWeb users and developpers
Section: Apps/Programming
Format: HTML
Index: /usr/share/doc/cubicweb-documentation/html/index.html
Files: /usr/share/doc/cubicweb-documentation/html/*