Major Japanese advertising agency ADK Holdings Inc. has reported to the fair trade watchdog that it participated in bid rigging for the rights to organize test events for the Tokyo Olympics, a source close to the matter said Tuesday. ADK came forward after Tokyo prosecutors recently launched an investigation into bid-rigging allegations in connection with the test events, in addition to a scandal involving the alleged receipt by a former games organizing committee executive of nearly 200 million yen ($1.41 million) in bribes from five companies, including ADK. By reporting the alleged violatio…