Sydney Sweeney is unbothered. The “Euphoria” actress cheekily reacted to the backlash over her new stripped-down sports betting ad with Novig — by posting even more snaps on social media. “it’s gamedayyy @novig #novigpartner,” she captioned the Instagram post on Sunday, which marked the first Sunday Night Football game of the season. Sweeney also took to her Instagram Stories to share images of several athletes — including Serena Williams, Ronda Rousey, Karl-Anthony Towns, Jason Kelce and more — who have posed sans clothing for different covers of ESPN’s Body Issue. The “Housemaid” star did not reveal why she posted the covers. Page Six…