Add PreventFailingBuildIT in qa/smoke-test-watcher

The watcher tests were recently marked with `@Network`, which prevents them from
normally being run. Unfortunately, this means no tests run by default and the
entire suite fails.

Original commit: elastic/x-pack-elasticsearch@40cfc75b26

qa/smoke-test-watcher/src/test/java/org/elasticsearch/smoketest/PreventFailingBuildIT.java

@@ -0,0 +1,19 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License;
+ * you may not use this file except in compliance with the Elastic License.
+ */
+package org.elasticsearch.smoketest;
+
+import org.elasticsearch.test.ESIntegTestCase;
+
+public class PreventFailingBuildIT extends ESIntegTestCase {
+
+    public void testSoThatTestsDoNotFail() {
+        // Noop
+
+        // This is required because SmokeTestWatcherClientYamlTestSuiteIT
+        // requires network access, so if network tests are not enable no
+        // tests will be run in the entire project and all tests will fail.
+    }
+}