[RTADPA BW Tests] quick fix for Hlt1 BW test. len(inputs) < 2 breaks logging string

As can be seen https://eoslhcbhttp.cern.ch//eos/lhcb/storage/lhcbpr/logs/Moore/AllenInMoore_hlt1_bandwidth/lhcb-master.2230_2023-11-30_05:18:53_+0100/run.log the Hlt1 test currently breaks.

Upon further investigation it seems to just be because simply just because it only downloads a single file and the logging requires 'input[0], input[1]'.

Simple fix to instead only print input[0] if len(inputs) < 2, so it will still break if len(inputs)=0, i.e. correctly breaking but won't break for len(inputs)>=1.