(Changes &aposweigh&apos to &aposweighs&apos in headline)* Optimism around ECB stress tests is short-lived* German Ifo index falls to lowest in almost 2 years* Wall Street set to open down ahead of data* Italy&aposs Monte Paschi drags down bank share index* Brazil markets suffer losses after Rousseff election winBy John GeddieLONDON, Oct 27 (Reuters) - European shares and the euro gave up early ga