WIP: Fix connection to sequence filter for multi-jet chains

In createDataFlow in HLTCFConfig, the chain leg names were being passed to the sequence filters. This doesn't work for multi-jet chains, where there is only one "leg" even in the case of multi-jet requirements. I worked round this by only splitting into the legs for the case of Combo chains (multi-jet chains are not combo because only a single hypo is needed).

Note, this might have to be revisited once we try to do jet + X (X=muon, electron etc) chains.