we need to change the fixture to have a tmp_path for mss_dir #2958
Description
When this occures, rather seldom, it looks like https://github.com/Open-MSS/MSS/blob/develop/tests/constants.py was not used.
We maybe should find a different solution than using the python namespace.
It is not the constants definition, rather the msui_settings.json or its defaults. Only there is a ~/mss.
On tests that should not be always the same dir.
Originally posted by @ReimarBauer in #2947