[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.

../../doc/book usr/share/doc/cubicweb-documentation
../../doc/html usr/share/doc/cubicweb-documentation
../../debian/cubicweb-doc usr/share/doc-base/cubicweb-doc