[entities] Optimize CWUser.properties. This property gets called each time a user connects to a repository, which means a lot. This optimisation cuts its execution time by 5 according to my tests

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