The latest flare-up between Saudi Arabia and the United Arab Emirates over Yemen looks dramatic on the surface, but OPEC cohesion, not missiles or militias, is what ultimately matters to the oil markets, which is why the latest public spat between Saudi Arabia and the UAE over Yemen created just a temporary blip in crude prices. Saudi forces intercepted this week what they said was an unauthorized UAE-linked shipment of weapons and military equipment destined for southern Yemen. The Saudi-led coalition dished out an airstrike on the southern Yemeni…