Update low-mass-dielectron hlt2 line hlt1-filter-code to match new hlt1 line names

The old HLT1 line names (e.g. Hlt1LowMassNoipDielectron_massSlice1_prompt) have been changed (e.g. to Hlt1LowMassDiElectron_massSlice1_prompt) because the lines do in fact have IP cuts (to separate 'prompt' and 'displaced').

Responding to this helpful comment from @rjhunter and introducing a dependency on Allen!1175 (merged). For testing, both will need to be included to get meaningful results.