**Build scan:**
https://gradle-enterprise.elastic.co/s/aodpvg6m2oba4/tests/:x-pack:plugin:ilm:internalClusterTest/org.elasticsearch.xpack.ilm.DataTiersMigrationsTests/testUserOptsOutOfTierMigration

**Reproduction line:**
`./gradlew ':x-pack:plugin:ilm:internalClusterTest' --tests "org.elasticsearch.xpack.ilm.DataTiersMigrationsTests.testUserOptsOutOfTierMigration" -Dtests.seed=D3FF350541188AFA -Dtests.locale=ar-IQ -Dtests.timezone=Asia/Famagusta -Druntime.java=18`

**Applicable branches:**
8.1

**Reproduces locally?:**
No

**Failure history:**
https://gradle-enterprise.elastic.co/scans/tests?tests.container=org.elasticsearch.xpack.ilm.DataTiersMigrationsTests&tests.test=testUserOptsOutOfTierMigration

**Failure excerpt:**
```
java.lang.AssertionError: 
Expected: is "warm"
     but: was "new"

  at org.hamcrest.MatcherAssert.assertThat(MatcherAssert.java:18)
  at org.junit.Assert.assertThat(Assert.java:956)
  at org.junit.Assert.assertThat(Assert.java:923)
  at org.elasticsearch.xpack.ilm.DataTiersMigrationsTests.lambda$testUserOptsOutOfTierMigration$3(DataTiersMigrationsTests.java:192)
  at org.elasticsearch.test.ESTestCase.assertBusy(ESTestCase.java:1070)
  at org.elasticsearch.xpack.ilm.DataTiersMigrationsTests.testUserOptsOutOfTierMigration(DataTiersMigrationsTests.java:187)
  at jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
  at java.lang.reflect.Method.invoke(Method.java:577)
  at com.carrotsearch.randomizedtesting.RandomizedRunner.invoke(RandomizedRunner.java:1758)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$8.evaluate(RandomizedRunner.java:946)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$9.evaluate(RandomizedRunner.java:982)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$10.evaluate(RandomizedRunner.java:996)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at org.apache.lucene.util.TestRuleSetupTeardownChained$1.evaluate(TestRuleSetupTeardownChained.java:44)
  at org.apache.lucene.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:43)
  at org.apache.lucene.util.TestRuleThreadAndTestName$1.evaluate(TestRuleThreadAndTestName.java:45)
  at org.apache.lucene.util.TestRuleIgnoreAfterMaxFailures$1.evaluate(TestRuleIgnoreAfterMaxFailures.java:60)
  at org.apache.lucene.util.TestRuleMarkFailure$1.evaluate(TestRuleMarkFailure.java:44)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl$StatementRunner.run(ThreadLeakControl.java:375)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl.forkTimeoutingTask(ThreadLeakControl.java:824)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl$3.evaluate(ThreadLeakControl.java:475)
  at com.carrotsearch.randomizedtesting.RandomizedRunner.runSingleTest(RandomizedRunner.java:955)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$5.evaluate(RandomizedRunner.java:840)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$6.evaluate(RandomizedRunner.java:891)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$7.evaluate(RandomizedRunner.java:902)
  at org.apache.lucene.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:43)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at org.apache.lucene.util.TestRuleStoreClassName$1.evaluate(TestRuleStoreClassName.java:38)
  at com.carrotsearch.randomizedtesting.rules.NoShadowingOrOverridesOnMethodsRule$1.evaluate(NoShadowingOrOverridesOnMethodsRule.java:40)
  at com.carrotsearch.randomizedtesting.rules.NoShadowingOrOverridesOnMethodsRule$1.evaluate(NoShadowingOrOverridesOnMethodsRule.java:40)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at org.apache.lucene.util.TestRuleAssertionsRequired$1.evaluate(TestRuleAssertionsRequired.java:53)
  at org.apache.lucene.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:43)
  at org.apache.lucene.util.TestRuleMarkFailure$1.evaluate(TestRuleMarkFailure.java:44)
  at org.apache.lucene.util.TestRuleIgnoreAfterMaxFailures$1.evaluate(TestRuleIgnoreAfterMaxFailures.java:60)
  at org.apache.lucene.util.TestRuleIgnoreTestSuites$1.evaluate(TestRuleIgnoreTestSuites.java:47)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl$StatementRunner.run(ThreadLeakControl.java:375)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl.lambda$forkTimeoutingTask$0(ThreadLeakControl.java:831)
  at java.lang.Thread.run(Thread.java:833)

```
x-pack/plugin/ilm/src/main/java/org/elasticsearch/xpack/ilm/PolicyStepsRegistry.java
}
    SortedMap<String, LifecyclePolicyMetadata> getLifecyclePolicyMap() {
        return lifecyclePolicyMap;
    }
    Map<String, Step> getFirstStepMap() {
        return firstStepMap;
    }
    Map<String, Map<Step.StepKey, Step>> getStepMap() {
        return stepMap;
    }
    public void update(IndexLifecycleMetadata meta) {
        assert meta != null : "IndexLifecycleMetadata cannot be null when updating the policy steps registry";
        
        cachedSteps.clear();
        DiffableUtils.MapDiff<String, LifecyclePolicyMetadata, Map<String, LifecyclePolicyMetadata>> mapDiff = DiffableUtils.diff(
            lifecyclePolicyMap,
            meta.getPolicyMetadatas(),
            DiffableUtils.getStringKeySerializer(),
            
            
            
            
            new DiffableUtils.NonDiffableValueSerializer<>() {
                @Override
                public void write(LifecyclePolicyMetadata value, StreamOutput out) {
                    
                    throw new UnsupportedOperationException("should never be called");
                }
                @Override
                public LifecyclePolicyMetadata read(StreamInput in, String key) {