Remember when the Shangri-Las and the Ronettes ruled the top 10? Well, once again there's a mini-industry in carefully packaged and marketed all-girl vocal groups; only the sound has changed. Like two similar outfits, the Cover Girls and Seduction, En Vogue delivers flirtatious R&B set to a mechanized beat. They're also scripted to their plucked eyebrows, from the ''dressing-room chatter'' (''Can I use your base?'') that opens their new, second album, Funky Divas, to the sexy choruses that chime in like clockwork. That said, the four sweet-voiced members of En Vogue are versatile enough to handle reggae-, gospel- and doo-wop-tinted dance music with game if not very deep enthusiasm. Still, Funky Divas has an awkward charm, especially on ''It Ain't Over Till the Fat Lady Sings,'' a shameless defense of the girls' fame, and ''What Is Love,'' in which they archly recite dictionary definitions of the word. En Vogue may end up a bonus question in music-trivia books of the year 2000, but in the meantime they're dancing all the way to the bank.