Changes to BW test options files to go with PRConfig!349

Goes with lhcb-datapkg/PRConfig!349 (merged) (and ideally lhcb-core/LHCbPR2HD!260 (merged))

See PRConfig MR for full description. Here the changes are:

• Remove 2 now-unnecessary options files,
• Don't hard-code paths to files; use a helper struct
• Some small refactoring (e.g. removing unnecessary loops)