The old-style simulation configuration uses ConfiguredFactory. This uses configuration methods defined in ...Config.py modules which are associated with a component name in various PackageNameConfigDb.py modules.
The new ComponentAccumulator-based configuration tends to use ...Config.py as the naming convention for the configuration modules, but in Simulation we have typically used ...ConfigNew.py to avoid a naming clash. This MR renames all the ConfiguredFactory ...Config.py modules to ...ConfigLegacy.py for packages under Simulation/G4Atlas. I will rename the ComponentAccumulator-based modules in a follow-up merge request, but I wanted to avoid this one getting too large.