updating codeowners
updating codeowners

For now, we will just have the main people that are working on terra as approvers. I don't see any reason to have the rules it is just making this too complicated. 

Removing @chriseclectic @antoniomezzacapo and @dcmckayibm as they are mainly focused on other parts of qiskit now and they can still do the pr and don't really need to focus on the approving.
QISKit/qiskit-sdk-py,QISKit/qiskit-sdk-py,QISKit/qiskit-sdk-py