MultiBodyJointFeedback returns two times the applied one

[Fixit-Davide]

While applying a Force/Torque over a joint and reading the feedback value (joint reaction forces) from the btMultiBodyJointFeedback the vector m_reactionForces returns exactly double the correct value. (i.e Torque of magnitude 1.0 over the Z-axis returns a feedback of 2.0).

I found this old discussion that might be related to the problem: https://github.com/bulletphysics/bullet3/discussions/3713

cc @Roncapat