ESCONDIDO, Calif., Oct. 25 — One is the most powerful Republican in the country. The other is among the most popular. But it took an inferno in Southern California to thaw the ice between President Bush and Gov. Arnold Schwarzenegger. It is no secret in California or Washington that the two have never been buddy-buddy, dating back to when Mr. Schwarzenegger was a top fitness adviser to Mr. Bush’s father. Mr. Bush thought little of Mr. Schwarzenegger’s first bid for governor and did not endorse him. Mr. Schwarzenegger has taken jabs at the president on such issues as climate change,...