Address android.os.cts.FileObserverTest#testFileObserver Ensure there are no events captured after stopWatching() is called on FileObserver. Bug: 396034979 Change-Id: I7f428c892941daff71f08f21b4ba4f0b4a160ef0 Signed-off-by: huangdezhi@hihonor.com Test: atest android.os.cts.FileObserverTest#testFileObserver Flag: EXEMPT minor fix