Passive joints are broken

[christophfroehlich]

As a consequence of #177 , passive joints don't work any more (try #172).

The joint is now fixed, even if no command interface is defined.

[christophfroehlich]

@AndyZe is this fallback which you introduced really needed?

gazebo_ros2_control/gazebo_ros2_control/src/gazebo_system.cpp

Lines 612 to 613 in 6458276

	// Fallback case is a velocity command of zero
	this->dataPtr->sim_joints_[j]->SetVelocity(0, 0.0);

Deleting it fixes passive joints again, see c043d80

[bmagyar]

That PR was fairly old I think when we merged it, it's not too surprising something wasn't fully aligned.

[bmagyar]

I'll make myself a reminder note to never merge wildly unscoped PRs in the future ;)

[christophfroehlich]

fixed with #237