[test] Simplify CWTC's init_authentication and assertAuthSuccess which shouldn't rely on removed .session attribute while it's not necessary and could be written in a simpler way.

mock
psycopg2
ldap3 < 2
cubicweb-basket
cubicweb-card
cubicweb-comment
cubicweb-file
cubicweb-localperms
cubicweb-tag