split again old- and new-style configuration of MagFieldService
split again old- and new-style configuration of MagFieldService into two seprate files after it was messed up in MR 27829
Basically re-doing what was done in !30181 (merged).
split again old- and new-style configuration of MagFieldService into two seprate files after it was messed up in MR 27829
Basically re-doing what was done in !30181 (merged).