cubicweb #3634164 [test] mess-up when several application home are used accross test [validation pending]

for instance in the container cube, there are some test using 'appid = some_other_data_directory' class attribute to use another directory as instance home. When all tests are run, sys.modules isn't properly cleanup up, leading to buggy import (eg data/entities.py loaded instead of some_other_data_directory/entities.py)

prioritynormal
typebug
done in3.17.14
load0.200
load left0.000
closed by#e2d5b0712974 [test] when the config change, we should cleanup sys.path and sys.modules. Closes #3634164
patch[test] when the config change, we should cleanup sys.path and sys.modules. Closes #3634164 [applied]