By Caroline Pailliez PARIS (Reuters) – Like quite a few on the left, 60-year-old nurse assistant Isabelle-Touria Boumhi says backing either Emmanuel Macron or Marine Le Pen in France’s presidential runoff last Sunday would have been choosing “between the plague and cholera.” She did not vote. Instead, she is preparing to take part in May Day protests this coming Sunday. And, in what could foreshadow what a newly re-elected Macron may expect when he presses ahead with pro-business reforms, including a plan to push back retirement age, Boumhi says she will take to the streets as often as needed …