[devtools] qunit: only start firefox once per test The separate profile initialization step doesn't seem necessary anymore. This was due to the system-wide installation of the "Sage" Firefox extensions which breaks -url on a fresh profile. Removing this obnoxious extension allows us to launch Firefox in a standard way. Related to #5533333.

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