Routing bits - 2 `HltRoutingBits` banks

Two HltRoutingBits banks are now saved in HLT2 output ie.

evt['/Event/DAQ/RawEvent'].banks(LHCb.RawBank.HltRoutingBits).size()

is 2.

The first bank always has bit 46 "on" for all output files. The second bank is behaving as expected for the HLT2 streams.

Suggestion by @apearce to use the UpdateExistingRawBank function in

https://gitlab.cern.ch/lhcb/LHCb/-/blob/master/Hlt/HltDAQ/src/component/HltRoutingBitsWriter.h#L52