Duplicate loading data causes issue in edges_classifier class

This line (https://gitlab.cern.ch/gnn4itkteam/commonframework/-/blob/dev/gnn4itk_cf/stages/edge_classifier/edge_classifier_stage.py#L194-200) is duplicate since the data is already loaded in (https://gitlab.cern.ch/gnn4itkteam/commonframework/-/blob/dev/gnn4itk_cf/stages/edge_classifier/edge_classifier_stage.py#L111-120)

This also causes the program to crush for some cases.

I have to change it to:

dataset = getattr(self, data_name)