By Noah Barkin BERLIN (Reuters) - In the first German election since Europe's debt crisis erupted four years ago, voters are likely to give Angela Merkel a third term on Sunday, but may force her into a coalition with her leftist rivals and catapult a new anti-euro party into parliament. The vote is being closely watched by Berlin's European partners, with some hoping Chancellor Merkel will soften her approach towards struggling euro states like Greece if she is pushed into a 'grand coalition' with the Social Democrats (SPD). ...