By Sheila Dang (Reuters) – Wall Street is bracing for the slowest global revenue growth in the history of the social media sector, as intensifying competition from TikTok and Apple in advertising threaten to compound economic woes in the second quarter. The dour expectations come after a blowout 2021, when social media ad sales in the United States grew 36% to reach $58 billion as brands increased marketing budgets to recover from the pandemic and reach customers online. But social media platforms have since warned investors and employees that the tide is turning as inflation lingers around 40…