refactor: remove unused and unmaintained cubicweb/devtools/stresstester.py
requested to merge topic/default/remove-unused-and-unmaintained-cubicweb-devtools-stresstester-py into branch/default
This script has never been used since quite some time since even basic imports don't works anymore ("clock" is not in "time" anymore).
So I suggest that we either remove it (this MR) or fix it and make it more visible if we instead want to keep it.