The testNotificationsShownAndCleared test was not doing anything
because the list of notification to show was always empty.
This patch fixes this issue and actually makes the test loop on
non-empty collections, and also fixes another ordering issue in
assertions themselves, hidden until now by the first issue.
Test: runtest -x frameworks/base/tests/net/java/com/android/server/connectivity/NetworkNotificationManagerTest.java
Change-Id: I4837b1175d7c9133e9156e33acaa1e7e3341cc62