CPAlgorithms: change 'mc' to 'fullsim' in the config blocks metadata handling

This is technically a one-line change, but had to be propagated throughout the various CI tests and places that relied on the old string format.

In the future we might also want to change DataType.FastSim to distinguish between AF2 and AF3 (relevant for calibrations?), but I leave that to when we have a concrete use case.