Physics doesn't factor in scale

[robertdhernandez]

Operating system or device - Godot version:
Windows 10 - Godot Engine v2.2.alpha.custom_build dc6eefd

Issue description (what happened, and what was expected):
Changing the scale of an object that uses Rigidbody2D resets the scale at run-time.

Steps to reproduce:
Create a Rigidbody2D node
Attach a sprite for visual feedback (or print get_scale())
Change the scale on the Rigidbody2D node to any other value
Run the game

[robertdhernandez]

I found the problematic line here, and after making a dumb workaround (caching the scale), I discovered the root problem: the physics engine doesn't take scale into account.

[akien-mga]

I guess it's the same bug as #5734.