cubicweb-forge #3556538 get ride of DeprecationWarning [validation pending]

Use cw_set method instead of set_attributes/set_relations use assertCountEqual in tests

prioritynormal
typeenhancement
done in1.10.1
load0.200
load left0.000
closed by#4e193b4d2a98 [cleaning] get ride of DeprecationWarnings (closes #3556538)
patch[cleaning] get ride of DeprecationWarnings (closes #3556538) [applied]