Fix B->Xll sprucing lines filter codes functions
Fix to function in B->Xll sprucing lines which parses line name and produces filter codes (introduced in !2431 (merged)), comma missing in https://gitlab.cern.ch/lhcb/Moore/-/blame/master/Hlt/Hlt2Conf/python/Hlt2Conf/lines/rd/b_to_xll_spruce.py#L109 (thanks to @matzeni for spotting this get_hlt2_filter_code
-> parse_hlt2_filter_code
for clarity.