Make StandardCellWeightCalib.py CA-compatible

Triggered by the issues encountered by !49968 (merged): Make the python file StandardCellWeightCalib.py compatible with old and new-style flags.

This file mostly does string-manipulation to figure out what to do, not too much interaction with flags and athena-components. Therefore I concluded the best way forward is to make the file compatible with both flag-flavors. Each relevant method has now a new parameter flags defaulting to None. If it is not None, it is assumed to be a new-style AthConfigFlags-container that will be used instead of the globalflags.