It begins with a most Sundance-y premise: A frustrated middle-school drama teacher has been rejected by his girlfriend in favor of their boss, the smarmy principal, and thus the teacher decides to get his revenge via the power of theater. Such a set-up has all the makings of the sort of arch dark comedy long favored by the cineratti of Park City. But as the festival packs up in preparation for departure from its longtime home, perhaps it is best if such a premise, the foundation of the film The Musical, is left behind.  There’s a dated quality to director Giselle Bonilla’s film — or, more so, to its script by Alexander Heller. Its attempts at satire and subversion — making the prosaic world of suburban education a locus of noir obsession and operatic machination — feel imported from a cultural era long past, when it seemed novel to upend the outwardly banal and mainstream and reveal its squalid underbelly. The housewives were proven desperate long ago, squirmy and selfish teachers have been interfering with …