Summary:
Any failures in `test_objc` within the objc-test.sh script have been kept hidden as `xcpretty` was swallowing the exit code from xcodebuild.
Fixes the issue TheSavior brought up in #22470 where failing snapshot tests were not reflected on Circle.
Run on Circle CI and confirm `test_objc` fails (iOS tests *are* broken on master).
Pull Request resolved: https://github.com/facebook/react-native/pull/22562
Differential Revision: D13406987
Pulled By: hramos
fbshipit-source-id: 3f3da01ab4c0ad87077813b06d2fdf788f32f6b8