Disable shape scaling by default

We have it enabled by default currently:

https://github.com/playcanvas/engine/blob/a223a892950e557af942f409d986ddd417257e0b/src/framework/physics/physics-world.js#L184-L195

This adds an extra loop every step to check if a component's entity was scaled. Which adds an overhead for projects that did not rely on that functionality previously. I think we should probably false it by default, unless a user needs to change scales at runtime - they can then enable it for some cost. This will affect projects that use hundreds of rigibodies.