Would widespread Bitcoin adoption reduce global economic growth?

Short answer: no.

Long answer: World economic growth is caused by reduction of cost and discovery of resources. Endless growth is completely possible, but at a certain point that growth becomes so small it's statistically 0. That point is where we are teleporting and instantly communicating, in a disease-free utopia where everyone lives forever. No further transaction needs to take place beyond that point, and no additional transaction would grow the economy. Bitcoin's transaction ability alone has the potential to greatly improve economic growth by reducing the cost that the entire currency industry incurs to keep running.

Now, individual country's wealth is a completely different story, since there are always more resources on the other side of the fence, unlike the earth, which has to eventually extent to another planet to discover more.