DerivationFrameworkConfiguration: Allow multiple children (augmentations) per parent (primary stream)

This is a follow-up to !58316 (merged). With this MR, we update the CA-based derivation configuration to allow multiple children (augmentations) per parent (primary stream), e.g.:

#!/bin/bash
ATHENA_CORE_NUMBER=4 Derivation_tf.py \
  --CA 'True' \
  --maxEvents '2000' \
  --multiprocess 'True' \
  --sharedWriter 'True' \
  --inputAODFile '/cvmfs/atlas-nightlies.cern.ch/repo/data/data-art/Tier0ChainTests/data18_13TeV.00357772.physics_Main.recon.AOD.r13286/AOD.27654050._000557.pool.root.1' \
  --outputDAODFile 'pool.root' \
  --formats 'PHYS' 'LLP1' 'FTAG2' \
  --augmentations 'LLP1:PHYS' 'FTAG2:PHYS'

This will result in:

$ root -l DAOD_PHYS.pool.root 
[...]
root [1] CollectionTree->GetEntries()
(long long) 2000
root [2] CollectionTree_DAOD_LLP1->GetEntries()
(long long) 659
root [3] CollectionTree_DAOD_FTAG2->GetEntries()
(long long) 39

cc: @jcatmore @gemmeren