By Ryan Woo BEIJING (Reuters) -Giant Christmas trees adorned with lights, tinsel and gift boxes greet shoppers at glittering malls in big Chinese cities like Shanghai and Chongqing, but in many parts of China, extending season’s greetings is out of the question. In southwest Yunnan province, a property management company issued a notice to shopping mall tenants urging them not to sell Christmas cards and presents and to even refrain from hanging decorations, saying foreign traditions should not be “blindly” followed, and one should be confident in one’s own culture. Schools in some cities from…