BEIJING, Sept 16 (Reuters) - General Li Shangfu, a veteran of China's military modernisation drive, rose through the ranks to become defence minister this year. Within six months, he disappeared under the cloud of a corruption probe. Li grew to prominence under President Xi Jinping's pursuit of military might during his decade in power while China's relations with the United States soured over issues including Taiwan, the democratically governed island that Beijing claims. But part of Xi's drive to improve his fighting force has been to stamp out corruption that has long plagued China's military and other state institutions. A...