(Reuters) - London's FTSE 100 joined a rally in global bourses on Friday as China's economic growth met expectations despite its trade war with the United States, while IAG jumped after it scrapped a rule capping ownership of its shares by non-Europeans.The FTSE 100 added 0.4%, boosted by miners , as well as British Airways-owner IAG , which rose 5.3% to its highest level since Sept. 2018.The midcap FTSE 250 advanced 0.3%. But motor insurer Hastings slid 8% after it forecast a slump in annual..