(Reuters) – A large majority of French oppose raising the legal retirement age, an opinion poll published by Les Echos newspaper showed, which could be an issue for President Emmanuel Macron, who has made that a key proposal as he seeks re-election this month. Macron has proposed pushing the legal age at which one can receive a full pension to 65 from 62. The far-right’s Marine Le Pen would bring it down to 60 for some workers and the hard-left’s Jean-Luc Melenchon for all. Conservative Valerie Pecresse and far-right Eric Zemmour, who are lower in the polls, would also have people retire later…