ListeningPortsTest: fix retry logic

In the rewrite of ListeningPortsTest (commit 8ed56018345305650eebe4069dbce0c8086a9d8d),
we stopped using ListeningPortsAssertionError for our assertion failures.
This prevented the UDP retry logic in assertNoRemotelyAccessibleListeningUdpPorts
from being effective.

Throw a ListeningPortsAssertionError instead of calling fail to allow
the retry logic to work again.

Bug: 11236346
Change-Id: I4912343a77a44e2cb1dea7961bf3d5f48cf6541a
diff --git a/tests/tests/security/src/android/security/cts/ b/tests/tests/security/src/android/security/cts/
index 6d42a8e..87e957d 100644
--- a/tests/tests/security/src/android/security/cts/
+++ b/tests/tests/security/src/android/security/cts/
@@ -197,7 +197,7 @@
         if (!errors.equals("")) {
-            fail(errors);
+            throw new ListeningPortsAssertionError(errors);