Gail Collins: Time to throw Rudy under the bus

Memo to Donald Trump: Throw Rudy Giuliani under a bus.Everything’s going wrong for the White House right now. We just had a Trump-appointed ambassador telling the impeachment hearing that there was indeed a quid pro quo in Ukraine, and everybody knew it.Most of the Democrats’ witnesses seem both sympathetic and believable. The Republicans produced a diplomat who instantly started telling the room what a terrific, honorable guy Joe Biden is.And no fair saying this is boring. Tell me y