**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
}
                    }
                }
            }
            """);
        
        assertBusy(() -> {
            final Response searchResponse = client().performRequest(searchRequest);
            assertOK(searchResponse);
            var responseMap = entityAsMap(searchResponse);
            assertThat((Integer) XContentMapValues.extractValue("hits.total.value", responseMap), greaterThan(0));
            refreshIndex(dest, RequestOptions.DEFAULT);
        }, 30, TimeUnit.SECONDS);
        stopTransform(config.getId());
        deleteTransform(config.getId());
    }
    public void testStopWaitForCheckpoint() throws Exception {
        String indexName = "wait-for-checkpoint-reviews";
        String transformId = "transform-wait-for-checkpoint";
        createReviewsIndex(indexName, 1000, NUM_USERS, TransformIT::getUserIdForRow, TransformIT::getDateStringForRow);
        Map<String, SingleGroupSource> groups = new HashMap<>();
        groups.put("by-day", createDateHistogramGroupSourceWithCalendarInterval("timestamp", DateHistogramInterval.DAY, null));
        groups.put("by-user", new TermsGroupSource("user_id", null, false));
        groups.put("by-business", new TermsGroupSource("business_id", null, false));
        AggregatorFactories.Builder aggs = AggregatorFactories.builder()
            .addAggregator(AggregationBuilders.avg("review_score").field("stars"))
            .addAggregator(AggregationBuilders.max("timestamp").field("timestamp"));
        TransformConfig config = createTransformConfigBuilder(
            transformId,
            "reviews-by-user-business-day",