Fix iOS screen recording
Fix iOS screen recording

Summary: It looks like the iOS simulator screen recording tool expects a SIGINT instead of a SIGKILL (the default of node's ChildProcess.kill()) to indicate it should stop recording, save the video file and die cleanly.

Reviewed By: danielbuechele

Differential Revision: D9480678

fbshipit-source-id: 5f17bd288c7622ffa3c337cef311e5e4e462218a

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