Apple EarPods buzzing except when I'm touching the area around the MacBook Trackpad
It's likely that your MacBook isn't properly grounded. This probably explains the buzzing sound that you are hearing.

When you are touching the aluminium surface of your MacBook, you are technically creating a way for the charge to move, technically providing the grounding, which explains why the buzzing stops.

It is recommended to use the adapter with a three pin extension cord. When using it, your MacBook gets grounded, preventing any change from staying and generating the buzzing sound.