ProtoParticleUnpacker - Make compatible with dd4hep

See QM test

https://lhcb-nightlies.web.cern.ch/nightly/lhcb-master-mr/4420/Moore/x86_64_v2-centos7-gcc11%2Bdd4hep-opt/tests#Hlt2Conf.sprucing.test_spruce_all_lines_analytics

ProtoParticleUnpacker                 FATAL  Standard std::exception is caught 
ProtoParticleUnpacker                 ERROR Expected a ':' in condition key /dd/Structure/LHCb
HLTControlFlowMgr                     FATAL Event failed in Node ProtoParticleUnpacker/ProtoParticleUnpacker

@graven @sesen FYI

Edited by Christopher Rob Jones
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