FIx async search tests - do not warn on the presence of .async-search (#117301) (#117372)

(cherry picked from commit f325c1541088995f35e7d39cf181a9b970d3c90a)

# Conflicts:
#	muted-tests.yml
#	test/framework/src/main/java/org/elasticsearch/test/rest/ESRestTestCase.java

test/framework/src/main/java/org/elasticsearch/test/rest/ESRestTestCase.java

@@ -1170,6 +1170,7 @@ public abstract class ESRestTestCase extends ESTestCase {
             }
             final Request deleteRequest = new Request("DELETE", Strings.collectionToCommaDelimitedString(indexPatterns));
             deleteRequest.addParameter("expand_wildcards", "open,closed" + (includeHidden ? ",hidden" : ""));
+            deleteRequest.setOptions(deleteRequest.getOptions().toBuilder().setWarningsHandler(ignoreAsyncSearchWarning()).build());
             final Response response = adminClient().performRequest(deleteRequest);
             try (InputStream is = response.getEntity().getContent()) {
                 assertTrue((boolean) XContentHelper.convertToMap(XContentType.JSON.xContent(), is, true).get("acknowledged"));
@@ -1182,6 +1183,30 @@ public abstract class ESRestTestCase extends ESTestCase {
         }
     }
 
+    // Make warnings handler that ignores the .async-search warning since .async-search may randomly appear when async requests are slow
+    // See: https://github.com/elastic/elasticsearch/issues/117099
+    protected static WarningsHandler ignoreAsyncSearchWarning() {
+        return new WarningsHandler() {
+            @Override
+            public boolean warningsShouldFailRequest(List<String> warnings) {
+                if (warnings.isEmpty()) {
+                    return false;
+                }
+                return warnings.equals(
+                    List.of(
+                        "this request accesses system indices: [.async-search], "
+                            + "but in a future major version, direct access to system indices will be prevented by default"
+                    )
+                ) == false;
+            }
+
+            @Override
+            public String toString() {
+                return "ignore .async-search warning";
+            }
+        };
+    }
+
     protected static void wipeDataStreams() throws IOException {
         try {
             if (hasXPack()) {