Flexible - able to switch between big-picture (which could also be called business-oriented) and detailed analytical mindsets at need.
Inside-out thinking - able to find gaps between expectations & reality, between assumptions & expectations, and so forth.
Integrated - which starts with systems thinking and goes from there.
I second @devtotest on being able to think at strange angles (or orthogonal) - I’ve heard it called “thinking outside the box” which tends not to describe testers quite so much as “Where is this box everyone keeps talking about?”