[ATR-24442] Combine L1 and HLT menus to make MC-"SMK" hash value

See [ATR-24442]

This fixes an issue we would have run into in the future with the initial implementation of hashes SMK values for MC.

As we only save a single number per event here, we need the same hashes SMK for L1 and HLT. We hence should combine these prior to hashing.