Add explicit CellLink SG Key in configuration, ATLASRECTS-4821

Should fix ATLASRECTS-4821

2:23:01 StoreGateSvc_Impl                                 WARNING  setupProxy:: error setting up proxy for key EgammaDummyCellLink and clid 1134620868
12:23:01  Pre-existing valid DataProxy @0x111067840 found in Store for key EgammaDummyCellLink with clid 1134620868
12:23:01 ClassIDSvc                                           INFO  getRegistryEntries: read 31 CLIDRegistry entries for module ALL
12:23:01 StoreGateSvc_Impl                                 WARNING record_impl: Problem setting up the proxy for object @0x111511a80
12:23:01  recorded with key EgammaDummyCellLink of type CaloClusterCellLinkContainer (CLID 1134620868) in DataObject @0x111310760
12:23:01 VarHandle(StoreGateSvc+EgammaDummyCellLink[1134...  ERROR FILE:LINE (StatusCode SG::VarHandleBase::record_impl(std::unique_ptr<DataObject>, void*, bool, bool)): code 0: recordObject failed