Eugene Lynch’s production of “Maid Made Boss,” Pinchgut Opera’s latest presentation, revealed so convincingly what conductor Erin Helyard had spoken-of in a podcast on the company’s website: just how pivotal “La serva padrona” (to use the 1733 work’s original title) must have been in the history of opera, particularly when seen in France (home of the tragédie-lyrique) some 16 years after composer Pergolesi’s death.