[devtools/test] Skip qunit tests in case of timeout
Follow-up on 87443f279b0f where other similar tests got
adjusted not to fail (in particular in our CI environment).
missing-dep-for-interpreter make => make | build-essential | dpkg-dev (usr/*/cubicweb/skeleton/debian/rules)
embedded-javascript-library usr/share/cubicweb/cubes/shared/data/jquery.js