[madgraph2021 postfix v0.6] Complete mg2021 mr !646 with changes suggested by giordano

Complete mg2021 mr !646 (merged) with changes suggested by giordano

assigned to @valassi

Hi @giordano thanks for the comments on !646 (merged) I am adding a further patch here I stopped the pipeline and will restart it by merging these changes too

mentioned in commit 90148225

merged

mentioned in merge request !646 (merged)

mentioned in merge request !648 (merged)

changed title from Complete mg2021 mr !646 (merged) with changes suggested by giordano to [madgraph2021 postfix v0.6] Complete mg2021 mr !646 (merged) with changes suggested by giordano