remove hard-coded tags for the MARC-based call number variable in the TPAC

[Jason Etheridge]

In opac/parts/misc_util.tt2, we define and populate args.marc_cns and args.marc_cn based on the contents of 092/099 tags. Instead, we should find the appropriate "Default Classification Scheme" library setting if it exists and use the defined tags and subfields in the corresponding row asset.call_number_class