[migration/test] avoid test interdependency by removing fakecustomtype cube There is still a failing test afterward but it doesn't seem related to changes in this series.

usr/bin/cubicweb-ctl usr/bin/
usr/lib/python2*/*-packages/cubicweb/cwctl.py
../cubicweb-ctl.bash_completion etc/bash_completion.d/cubicweb-ctl