CP Algorithm Block Config: Update postfix used for ftag, electron WP, etc. to selectionName.
The name postfix is used for many of the CP config blocks as second arguement to the initialization but the postfix often corresponds to the name given to the selection name in other CP blocks such as MET and overlap removal. In order to make the name more meaningful, it has been changed to selectionName.
This merge request addresses: ATLASG-2607