scripts/merge_user.py: remove obsolete user_name column
scripts/merge_user.py: remove obsolete user_name column

RBE-Avionik/skylines,Harry-R/skylines,snip/skylines,Turbo87/skylines,snip/skylines,Turbo87/skylines,skylines-project/skylines,snip/skylines,Harry-R/skylines,RBE-Avionik/skylines,skylines-project/skylines,Turbo87/skylines,skylines-project/skylines,kerel-fs/skylines,kerel-fs/skylines,shadowoneau/skylines,Harry-R/skylines,kerel-fs/skylines,Turbo87/skylines,RBE-Avionik/skylines,Harry-R/skylines,RBE-Avionik/skylines,shadowoneau/skylines,skylines-project/skylines,TobiasLohner/SkyLines,shadowoneau/skylines,shadowoneau/skylines,TobiasLohner/SkyLines,TobiasLohner/SkyLines