By Gabriela Baczynska BRUSSELS (Reuters) - In a rundown old factory in Belgium, Holocaust survivor Simon Gronowski celebrated his upcoming 90th birthday on Sunday by starring in an opera inspired by his life - a history of love, faith and forgiveness overcoming the darkest tragedy. Gronowski was 11 years old and living Brussels when in 1943 Nazis put him, his mother and sister on a train bound for Auschwitz, the infamous death camp in Nazi-occupied Poland. The train was briefly stopped by three Belgian resistance fighters in Boortmeerbeek, 30 kilometres (19 miles) northeast of Brussels. In the...