Flaky test: AppHostExitsWhenCliProcessPidDies

[mitchdenny]

https://dev.azure.com/dnceng-public/public/_build/results?buildId=998429&view=ms.vss-test-web.build-test-results-tab&runId=26645458&resultId=100003&paneView=debug

[mitchdenny]

Moving to backlog this is a really rare failure. The issue is understood. The If the remote executor returns very quickly it hits a race condition.