Do not add MuGirl related tag_maps to MuonCreatorAlg_LRT if MuGirl off.

While trying to debug something else, I spotted the following error:

WARNING StoreGate/src/VarHandleBase.cxx:848 (void*SG::VarHandleBase::typeless_dataPointer_impl(bool)): could not get proxy for key MuGirlMap_LRT

This should fix it. Tagging @jojungge