Changes to Get agent group list

added the media type application/json for the response with the status 200

added the non-success response with the status 400

added the non-success response with the status 401

added the non-success response with the status 403

added the non-success response with the status 404

added the non-success response with the status 409

added the non-success response with the status 429

added the non-success response with the status 500