By Alexandra Ulmer and Jason Lange (Reuters) -From Wall Street to Silicon Valley, wealthy donors have thrown tens of millions of dollars at Republican U.S. presidential candidate Nikki Haley in an effort to keep Donald Trump from returning to the White House. They have learned a hard lesson: Big money cannot win the Republican presidential nomination, at least not against Trump, who holds the support of a wide majority of the party’s voters. Pro-Haley forces outspent the main outside group supporting the former president’s candidacy by more than two to one over the past year, according to a Re…