MEGA Sydney Sweeney is garnering negative feedback as she strips down to cheeky undies to promote her lingerie brand’s latest drop. The 28-year-old actress, who launched SYRN in January, is fresh from debuting her Small Town Girl collection, which she aptly promoted by posing inside a trailer. Ditching the glamorous settings typically used by celebrities, Sydney kept things simple and ordinary while inside a basic trailer, but there was nothing …