Mute NodeSubclassTests#testReplaceChildren (#52952)

Relates #52951

x-pack/plugin/ql/src/test/java/org/elasticsearch/xpack/ql/tree/NodeSubclassTests.java

@@ -153,6 +153,7 @@ public class NodeSubclassTests<T extends B, B extends Node<B>> extends ESTestCas
     /**
      * Test {@link Node#replaceChildren} implementation on {@link #subclass}.
      */
+    @AwaitsFix(bugUrl = "https://github.com/elastic/elasticsearch/issues/52951")
     public void testReplaceChildren() throws Exception {
         Constructor<T> ctor = longestCtor(subclass);
         Object[] nodeCtorArgs = ctorArgs(ctor);