This looks to be a newly added test in #89573 and the failure reproduces for me locally.

**Build scan:**
https://gradle-enterprise.elastic.co/s/pjik5yk3efeiy/tests/:x-pack:plugin:core:test/org.elasticsearch.xpack.core.ml.action.StartTrainedModelDeploymentRequestTests/testValidate_GivenQueueCapacityIsAtLimit

**Reproduction line:**
`./gradlew ':x-pack:plugin:core:test' --tests "org.elasticsearch.xpack.core.ml.action.StartTrainedModelDeploymentRequestTests.testValidate_GivenQueueCapacityIsAtLimit" -Dtests.seed=51860637808931AE -Dtests.locale=cs-CZ -Dtests.timezone=EAT -Druntime.java=17`

**Applicable branches:**
main

**Reproduces locally?:**
Yes

**Failure history:**
https://gradle-enterprise.elastic.co/scans/tests?tests.container=org.elasticsearch.xpack.core.ml.action.StartTrainedModelDeploymentRequestTests&tests.test=testValidate_GivenQueueCapacityIsAtLimit

**Failure excerpt:**
```
java.lang.AssertionError: 
Expected: is null
     but: was <org.elasticsearch.action.ActionRequestValidationException: Validation Failed: 1: [threads_per_allocation] must be a power of 2 less than or equal to 32;>

  at __randomizedtesting.SeedInfo.seed([51860637808931AE:A33E549418734690]:0)
  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.core.ml.action.StartTrainedModelDeploymentRequestTests.testValidate_GivenQueueCapacityIsAtLimit(StartTrainedModelDeploymentRequestTests.java:159)
  at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(NativeMethodAccessorImpl.java:-2)
  at jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
  at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
  at java.lang.reflect.Method.invoke(Method.java:568)
  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.tests.util.TestRuleSetupTeardownChained$1.evaluate(TestRuleSetupTeardownChained.java:44)
  at org.apache.lucene.tests.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:43)
  at org.apache.lucene.tests.util.TestRuleThreadAndTestName$1.evaluate(TestRuleThreadAndTestName.java:45)
  at org.apache.lucene.tests.util.TestRuleIgnoreAfterMaxFailures$1.evaluate(TestRuleIgnoreAfterMaxFailures.java:60)
  at org.apache.lucene.tests.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:390)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl.forkTimeoutingTask(ThreadLeakControl.java:843)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl$3.evaluate(ThreadLeakControl.java:490)
  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.tests.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:43)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at org.apache.lucene.tests.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.tests.util.TestRuleAssertionsRequired$1.evaluate(TestRuleAssertionsRequired.java:53)
  at org.apache.lucene.tests.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:43)
  at org.apache.lucene.tests.util.TestRuleMarkFailure$1.evaluate(TestRuleMarkFailure.java:44)
  at org.apache.lucene.tests.util.TestRuleIgnoreAfterMaxFailures$1.evaluate(TestRuleIgnoreAfterMaxFailures.java:60)
  at org.apache.lucene.tests.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:390)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl.lambda$forkTimeoutingTask$0(ThreadLeakControl.java:850)
  at java.lang.Thread.run(Thread.java:833)

```
x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/ml/action/StartTrainedModelDeploymentRequestTests.java
public void testValidate_GivenThreadsPerAllocationIsValid() {
        for (int n : List.of(1, 2, 4, 8, 16, 32)) {
            Request request = createRandom();
            request.setThreadsPerAllocation(n);
            ActionRequestValidationException e = request.validate();
            assertThat(e, is(nullValue()));
        }
    }
    public void testValidate_GivenNumberOfAllocationsIsZero() {
        Request request = createRandom();
        request.setNumberOfAllocations(0);
        ActionRequestValidationException e = request.validate();
        assertThat(e, is(not(nullValue())));
        assertThat(e.getMessage(), containsString("[number_of_allocations] must be a positive integer"));
    }
    public void testValidate_GivenNumberOfAllocationsIsNegative() {
        Request request = createRandom();
        request.setNumberOfAllocations(randomIntBetween(-100, -1));
        ActionRequestValidationException e = request.validate();
        assertThat(e, is(not(nullValue())));
        assertThat(e.getMessage(), containsString("[number_of_allocations] must be a positive integer"));
    }
    public void testValidate_GivenQueueCapacityIsZero() {
        Request request = createRandom();
        request.setQueueCapacity(0);
        ActionRequestValidationException e = request.validate();
        assertThat(e, is(not(nullValue())));
        assertThat(e.getMessage(), containsString("[queue_capacity] must be a positive integer"));
    }
    public void testValidate_GivenQueueCapacityIsNegative() {