“I used to babysit John Wick.” - Alice CooperCher; Alice Cooper; Kiefer SutherlandCredit: Franziska Krug/Getty; Jon Kopaloff/Getty; Karwai Tang/WireImageHollywood is smaller than you might think, and many stars who light up the screen have relationships that date back decades.Some used to be roommates. Others used to be classmates or coworkers. And some? Well, they were babysitting the stars of tomorrow. What are the odds? And why couldn’t that …