DUBAI, United Arab Emirates — Dubai, the emirate known for its celebration of over-the-top glamour and luxury, is racing ahead to dominate the Middle East’s plastic surgery market with plans to attract half a million medical tourists in six years. To cash in on the boom, Dubai has rolled out three-month renewable visas for medical tourists and their companions and started a campaign to brand itself as the Middle East’s top destination for wellness and plastic surgery. Vasilica Baltateanu, who started up the United Arab Emirates’ first plastic surgery consultancy, Vasilica Aesthetics, said Dubai’s glamour factor is driving the trend among the region’s well-heeled tourists who want to shop, indulge in spas and relax in opulent hotels.