Use xcconfig as default for FBXCTestKit
Use xcconfig as default for FBXCTestKit

Summary: This will make moving the project easier. All of these removed values are the same as the values in the `xcconfig` file.

Reviewed By: zsol

Differential Revision: D4956607

fbshipit-source-id: 168a797b705d99e2dd53c5bc2b2356a90ab6907d

StevenUpForever/FBSimulatorControl,facebook/FBSimulatorControl,facebook/FBSimulatorControl,StevenUpForever/FBSimulatorControl,StevenUpForever/FBSimulatorControl,facebook/FBSimulatorControl,StevenUpForever/FBSimulatorControl,facebook/FBSimulatorControl,facebook/FBSimulatorControl