[book] fix sphinx documentation generation (closes #2991997)
changeset 17994bf95d6a ([doc] update Session documentation) added
cubicweb.server.session.Session autodoc to the book. This caused errors
from sphinx due to a section title not being allowed in the class's
docstring.
[test/ldap] fix ldap tests
- make sure the url is properly updated on database setup (when the test
database already exists and the ldap URI has changed)
- fix the ldapuser test setup process.