[core] Adjust cw<3.21 compatibility
Most of cubibweb < 3.21 expects a ClientConnection as the main connection.
Related to #5731814
Closes #5878592
.. _auth_module:
:mod:`pyramid_cubicweb.auth`
----------------------------
.. automodule:: pyramid_cubicweb.auth
.. autofunction:: includeme
.. autoclass:: UpdateLoginTimeAuthenticationPolicy
:show-inheritance:
:members: