Macau was the place where Las Vegas Sands was going to step out from the shadows of its rivals. Its bold strategy — to grab the biggest share of the Chinese enclave’s gaming market with an Asian version of the Las Vegas Strip — swamped the company with debt that has taken it to the brink of bankruptcy. Now, image problems are cropping up in Macau, where the company’s chief executive, Sheldon Adelson, had been hailed as a visionary.