Mark WUT#testSerializeSearchRequest as awaits fix

This commit marks WatcherUtilsTests#testSerializeSearchRequest which is
failing with seed 97BC9E2543410D55 as awaits fix.

Original commit: elastic/x-pack-elasticsearch@45a174c1f2

elasticsearch/x-pack/watcher/src/test/java/org/elasticsearch/xpack/watcher/support/WatcherUtilsTests.java

@@ -85,6 +85,7 @@ public class WatcherUtilsTests extends ESTestCase {
         assertThat(result, equalTo(expected));
     }
 
+    @AwaitsFix(bugUrl = "https://github.com/elastic/x-plugins/issues/3134")
     public void testSerializeSearchRequest() throws Exception {
         String[] expectedIndices = generateRandomStringArray(5, 5, true);
         String[] expectedTypes = generateRandomStringArray(2, 5, true);