I think of science as a branch of philosophy. In other words, philosophy has traditionally been the means by which we explore and think about important questions of existence and life. Part of that exploration has always been epistemology and understanding the natural world.
When science was born, what really happened was that department of philosophy was reformed. Now, instead of Socratic argument to establish natural fact, we use the science.
But those facts of science should then form the basis of fact upon which all modern useful philosophy is built. It is the task of philosophers to then say, "ok if this is the world we live in, the one described by science, what is the best way to live, to be happy, and to find meaning in life?"
This question has been answered many times throughout history, and to the satisfaction of millions that have lived out their lives under one or more philosophies. But these answers will change over time so the questions must continually be re-examined. The reason they change is (1) because our global circumstances change due to social and technological evolution, and (2) because our understanding of the universe changes as scientific theory evolves, and to an extent, some of the philosophic questions are moderated by these conclusions.
Aside from the fact that the answer changes, these questions are so broad that it does take volumes to really reach the answers. So, no, science has opened up more questions that need to be asked by the philosopher, not less.
You ask how many "truths" of reality philosophers have discovered, as though they are in some competition with science when the two are different parts of the same field. Philosophy is not the "love of knowledge" - it is the "love of wisdom". There is a difference.