Waiting for idle in test

Waiting for idle in testRequestsSortedByIdSortsCorrectly to give it time
to handle async operations as part of registering network callbacks.

Bug: 177376544
Test: atest FrameworksNetTests:ConnectivityServiceTest#
testRequestsSortedByIdSortsCorrectly --rerun-until-failure 200

Change-Id: I268c4607d1a4c79e79f1385f014563cea0c2f979
diff --git a/tests/net/java/com/android/server/ConnectivityServiceTest.java b/tests/net/java/com/android/server/ConnectivityServiceTest.java
index 2e70be7..b7ade9e 100644
--- a/tests/net/java/com/android/server/ConnectivityServiceTest.java
+++ b/tests/net/java/com/android/server/ConnectivityServiceTest.java
@@ -8395,6 +8395,7 @@
         mCm.registerNetworkCallback(genericRequest, genericNetworkCallback);
         mCm.registerNetworkCallback(wifiRequest, wifiNetworkCallback);
         mCm.registerNetworkCallback(cellRequest, cellNetworkCallback);
+        waitForIdle();
 
         final ConnectivityService.NetworkRequestInfo[] nriOutput = mService.requestsSortedById();