By Katie Paul (Reuters) -Meta Platforms Inc Chief Operating Officer Sheryl Sandberg, whose close partnership with Chief Executive Officer Mark Zuckerberg powered the growth of the world’s biggest social network, is leaving the company after 14 years, she said in a Facebook post on Wednesday. The announcement initially sent the social media firm’s shares down 4%, but the stock was nearly flat in after hours trade. “When I took this job in 2008, I hoped I would be in this role for five years. Fourteen years later, it is time for me to write the next chapter of my life,” she wrote. Chief Growth O…