By Aziz El Yaakoubi and William James RIYADH/LONDON (Reuters) -British Prime Minister Boris Johnson held talks about energy security on Wednesday with the de facto leaders of Gulf oil exporters Saudi Arabia and the United Arab Emirates but secured no public pledge to ramp up production. Johnson’s trip to Abu Dhabi and Riyadh was aimed at securing oil supplies and raising pressure on President Vladimir Putin over Russia’s invasion of Ukraine, which led to sweeping Western sanctions on Moscow and soaring world energy prices. Johnson’s office said that in his meeting with Abu Dhabi Crown Prince S…