aosp/1622675 made handler to be nonnull but testRequestBackgroundNetwork still pass null as handler when calling requestBackgroundNetwork, so there is a NullPointerException when running testRequestBackgroundNetwork. Bug: 175662146 Test: atest CtsNetTestCases:ConnectivityManagerTest#testRequestBackgroundNetwork Change-Id: I871992549dfc8cc356221164f1dd49c64f0dae67