Don't append the global plan

[rokusottervanger]

We append the global plan with the carrot distance here:

https://github.com/nobleo/path_tracking_pid/blob/61c6cc828bd98dddd8cc14cbabdd62353a89ad3c/src/controller.cpp#L190-L196

But there are a few problems with this:

• this distance may change at runtime (dynamic reconfigure), and this is not reflected in the global plan,
• the last pose may not be in the direction of the end of the plan, making the direction in which we append the plan rather arbitrary,