RelBCID is only plotted from 0 to 16 in Online Monitor

The relBCID distribution is only plotted from 0 to 16 instead from 0 to 31. I guess we should fix this or does this have any reason?

See: https://gitlab.cern.ch/silab/bdaq53/blob/development/bdaq53/analysis/online_monitor/bdaq53_recv.py#L99-100 https://gitlab.cern.ch/silab/bdaq53/blob/development/bdaq53/analysis/online_monitor/bdaq53_recv.py#L127-130