Improve cancellation test for async DNS API

After having a lock between callback and cancellationsignal,
errno with EBADF should not happen.

Bug: 129317069
Test: atest DnsResolverTest
Change-Id: I08e800b078d40345eb3f46da1323db251c8dcd47

tests/cts/net/src/android/net/cts/DnsResolverTest.java

@@ -370,7 +370,6 @@ public class DnsResolverTest extends AndroidTestCase {
 
         @Override
         public void onQueryException(@NonNull ErrnoException e) {
-            if (mCancelSignal.isCanceled() && e.errno == EBADF) return;
             fail(mMsg + e.getMessage());
         }
     }