DUBAI/RIYADH Reuters) - State-owned oil giant Saudi Aramco's initial public offering (IPO) will be the biggest in history, but will still fall significantly short of the towering $2 trillion valuation long sought by Crown Prince Mohammed bin Salman. Aramco priced its IPO at 32 riyals ($8.53) per share, the top of its indicative range, the company said in a statement, raising $25.6 billion and beating Alibaba's record $25 billion listing in 2014. At that level, Aramco has a m