cubicweb #3025536 default schema graph display CWDataImport [validation pending]

while this is an internal type we shouldn't see

prioritynormal
typebug
done in3.17.4
load0.000
load left0.000
closed by#f3286e817f28 [schema] mark CWDataImport as an internal type. Closes #3025536
patch[schema] mark CWDataImport as an internal type. Closes #3025536 [applied]