Cleaned `MeanlibRobot` of unused prints and defs

[betapictoris]

Changes

• Removed printing in autonomous to match the other methods.
• Removed simulationPeriodic override as it doesn't exist within RobotBase.

[betapictoris]

We still want the println for autonomous so this shows up in the logs.

Wouldn't autonomous() be overridden anyway, or are there times when autonomous() is called without being overridden? If so, shouldn't we consider a more descriptive warning, such as "The autonomous mode was called without being overridden, consider overriding it to enable this mode"?

[jcrowell]

There are times where this might not be overridden. It might be nice to add a note to the comment indicating the autonomous was not overwritten but this is not strictly necessary.

[betapictoris]

I've added a message that tells the user that autonomous mode wasn't implemented by them.