Improve scaling of postprocessing tasks

[mgiulini]

Is your feature request related to a problem? Please describe. some scaling experiments on supercomputers allowed us to spot some execution bottlenecks at the postprocessing level. In this case, when the postprocessing is called at the end of a caprieval-free workflow, the parallelisation is not great, as it takes the parameter proper to the batch mode execution

Describe the solution you'd like It should be easy to call the postprocessing with the current running parameters (mode + number of cores) from within haddock3

Additional context This should save a lot of CPU time in these occasions. Goes also along the Bioexcel lines of improving the scaling of core applications.