**Found in version**
- Observed in 8.2.3, but might exist longer

**Steps to reproduce**
On a multi node cloud cluster (might also work on a local multi node cluster):
- Create a transform with a retention policy
- Update the transform and remove the retention policy

**Expected result**
- The retention policy is removed

**Actual result**
- This sometimes results in an error:
```
An error occurred calling the API endpoint to update transforms.
Bad Request: [illegal_argument_exception: [illegal_argument_exception] Reason: 
Unknown NamedWriteable [org.elasticsearch.xpack.core.transform.transforms.RetentionPolicyConfig][null_retention_policy]]:
Unknown NamedWriteable [org.elasticsearch.xpack.core.transform.transforms.RetentionPolicyConfig][null_retention_policy]
```

**Additional information**
- Quote from slack discussion with @benwtrent:
  > It wouldn’t happen if you hit a node that can execute the update immediately without serializing to a different node
x-pack/plugin/transform/qa/multi-node-tests/src/javaRestTest/java/org/elasticsearch/xpack/transform/integration/TransformIT.java
.endObject();
        Request putPipeline = new Request("PUT", "/_ingest/pipeline/" + pipelineId);
        putPipeline.setEntity(new StringEntity(Strings.toString(pipelineBuilder), ContentType.APPLICATION_JSON));
        assertOK(client().performRequest(putPipeline));
        String update = """
            {
                "description": "updated config",
                "dest": {
                   "index": "%s",
                   "pipeline": "%s"
                }
            }
            """.formatted(dest, pipelineId);
        updateConfig(id, update);
        
        long timeStamp = Instant.now().toEpochMilli() - 1_000;
        long user = 42;
        indexMoreDocs(timeStamp, user, indexName);
        
        waitUntilCheckpoint(config.getId(), 2L);
        int numDocsAfterCp2 = (Integer) XContentMapValues.extractValue("stats.documents_indexed", getTransformStats(config.getId()));
        assertThat(numDocsAfterCp2, greaterThan(docsIndexed));
        Request searchRequest = new Request("GET", dest + "/_search");
        searchRequest.addParameter("track_total_hits", "true");
        searchRequest.setJsonEntity("""
            {
                "query": {
                    "term": {
                        "static_forty_two": {
                            "value": 42