By Valentina Za and Gianluca Semeraro MILAN (Reuters) – Philippe Donnet kept his job as chief executive of Italian insurer Generali on Friday, surviving a challenge from rebel domestic investors who retained board seats and vowed to keep up the pressure for reform. The vote at the company’s annual general meeting (AGM) followed months of bitter infighting at the heart of Europe’s third-largest insurer and leaves a question mark over whether his main opponents will hang on to their combined 20% stake. Donnet called for unity after seeing off a challenge spearheaded by investor Francesco Gaetano…