test: fix ITDatabaseAdminTest failures (#2976)

* test: fix ITDatabaseAdminTest failures

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

* exclude owlbot pre-processor run on kokoro config

* remove reduntant assert

* fix test

---------

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

Author: rahul2393

google-cloud-spanner/src/test/java/com/google/cloud/spanner/it/ITDatabaseAdminTest.java

@@ -47,8 +47,10 @@
 import java.util.Optional;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
 import java.util.logging.Level;
 import java.util.logging.Logger;
+import org.junit.Assert;
 import org.junit.Before;
 import org.junit.ClassRule;
 import org.junit.Test;
@@ -260,9 +262,14 @@ public void updateDatabaseInvalidFieldsToUpdate() {
     OperationFuture<Database, UpdateDatabaseMetadata> op =
         dbAdminClient.updateDatabase(databaseToUpdate);
 
-    ExecutionException e =
-        assertThrows(ExecutionException.class, () -> op.get(5, TimeUnit.MINUTES));
-    assertThat(e.getMessage()).contains("Invalid field mask");
+    try {
+      op.get(5, TimeUnit.MINUTES);
+      Assert.fail("No exception thrown");
+    } catch (ExecutionException | InterruptedException | TimeoutException e) {
+      Assert.assertTrue(e.getCause() instanceof SpannerException);
+      SpannerException exception = ((SpannerException) e.getCause());
+      assertEquals(ErrorCode.INVALID_ARGUMENT, exception.getErrorCode());
+    }
   }
 
   @Test

owlbot.py

@@ -25,6 +25,7 @@
     excludes=[
         ".kokoro/continuous/common.cfg",
         ".kokoro/nightly/common.cfg",
+        ".kokoro/nightly/integration.cfg",
         ".kokoro/nightly/java8-samples.cfg",
         ".kokoro/nightly/java11-samples.cfg",
         ".kokoro/nightly/samples.cfg",