In current code, the test will call pressHome before show network notification but it does not verify the home screen is shown. The test might be failed due to the notification shade is still opened. Thus adding an assertion to verify the launcher is shown. Bug: 255643296 Test: FrameworksNetTest:NetworkNotificationManagerTest Change-Id: Iee3476a26030b9ba72994dee624e0e6974c9369f