Handle deprecation warnings in a permissive manner

Relates to #37290

Author: javanna

x-pack/qa/full-cluster-restart/src/test/java/org/elasticsearch/xpack/restart/MlMigrationFullClusterRestartIT.java

@@ -7,7 +7,9 @@
 
 import org.elasticsearch.Version;
 import org.elasticsearch.client.Request;
+import org.elasticsearch.client.RequestOptions;
 import org.elasticsearch.client.Response;
+import org.elasticsearch.client.WarningsHandler;
 import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.unit.TimeValue;
@@ -70,6 +72,9 @@ private void createTestIndex() throws IOException {
                 "\"airline\": {\"type\": \"keyword\"}," +
                 "\"responsetime\": {\"type\": \"float\"}" +
                 "}}}}");
+        RequestOptions.Builder options = createTestIndex.getOptions().toBuilder();
+        options.setWarningsHandler(WarningsHandler.PERMISSIVE);
+        createTestIndex.setOptions(options);
         client().performRequest(createTestIndex);
     }