Add a test verifying that when the device has detected a captive portal, or when the user is trying to login to a captive portal, the captive portal network does not become the default network if another network can provide internet access. This follows R CDD requirements. Test: atest CtsNetTestCases:android.net.cts.CaptivePortalTest Bug: 152280218 Change-Id: I6a97ed26dba665efdc67abb2371e0fc30ede020c