IpManagerTest: fix flaky test

Reset the callback mock for every onLinkPropertiesChange expected when
pushing address updates on the BaseNetworkObserver.

Bug: 32561414
Bug: 62918393
Test: runtest frameworks-net, IpManagerTest passes 200 times in a row
Change-Id: I4719b4dc86044438243887634191c2d21686b80f

tests/net/java/android/net/ip/IpManagerTest.java

@@ -180,7 +180,8 @@ public class IpManagerTest {
         // Add N - 1 addresses
         for (int i = 0; i < lastAddr; i++) {
             mObserver.addressUpdated(iface, new LinkAddress(addresses[i]));
-            verify(mCb, timeout(100).times(1)).onLinkPropertiesChange(any());
+            verify(mCb, timeout(100)).onLinkPropertiesChange(any());
+            reset(mCb);
         }
 
         // Add Nth address