Make FBLogicTestRunStrategy wait for file completion
Make FBLogicTestRunStrategy wait for file completion

Summary: Now that the file writing closing and opening is asynchronous via futures, we can then place this into the chain of futures.

Reviewed By: marekcirkos

Differential Revision: D6149647

fbshipit-source-id: 495b66891c637f8e24bd3419eb27347107164f73

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