By Jörn Poltz MUNICH (Reuters) - Austrian sensor maker AMS will go ahead with a takeover bid for Osram that values the German lighting group at 4.3 billion euros ($4.8 billion), it said on Wednesday, setting the stage for a potential bidding war. Osram said it had waived an agreement that so far has prevented AMS from making a bid to rival that of private equity investors Bain Capital and Carlyle , confirming an earlier Reuters story that had pushed Osram shares to a five-month high.