Drop 3.13 incomplete backward compat in edit controller. It is very old and broken (there is another non-backward-copmpatible usage of `_cw_entity_fields`), better to remove it instead of fixing. Closes #3515223.

usr/bin/cubicweb-ctl usr/bin/
usr/lib/PY_VERSION/*-packages/cubicweb/cwctl.py
../cubicweb-ctl.bash_completion etc/bash_completion.d/cubicweb-ctl