The problem seems to be an underlying timeout. However, without knowing the details, I wonder if a health should always return something and be robust against all kinds of underlying problems.

**Build scan:**
https://gradle-enterprise.elastic.co/s/5lqe2ng76yaru/tests/:server:internalClusterTest/org.elasticsearch.health.node.ShardsCapacityHealthIndicatorServiceIT/testGreen

**Reproduction line:**
```
./gradlew ':server:internalClusterTest' --tests "org.elasticsearch.health.node.ShardsCapacityHealthIndicatorServiceIT.testGreen" -Dtests.seed=F48280FCE8F284B8 -Dtests.locale=tr -Dtests.timezone=Asia/Baghdad -Druntime.java=17 -Dtests.fips.enabled=true
```

**Applicable branches:**
main

**Reproduces locally?:**
No

**Failure history:**
https://gradle-enterprise.elastic.co/scans/tests?tests.container=org.elasticsearch.health.node.ShardsCapacityHealthIndicatorServiceIT&tests.test=testGreen

**Failure excerpt:**
```
java.lang.AssertionError: (No message provided)

  at __randomizedtesting.SeedInfo.seed([F48280FCE8F284B8:174AAF9953EF04CA]:0)
  at org.junit.Assert.fail(Assert.java:86)
  at org.junit.Assert.assertTrue(Assert.java:41)
  at org.junit.Assert.assertNotNull(Assert.java:712)
  at org.junit.Assert.assertNotNull(Assert.java:722)
  at org.elasticsearch.health.node.ShardsCapacityHealthIndicatorServiceIT.findHealthNode(ShardsCapacityHealthIndicatorServiceIT.java:148)
  at org.elasticsearch.health.node.ShardsCapacityHealthIndicatorServiceIT.fetchShardsCapacityIndicatorResult(ShardsCapacityHealthIndicatorServiceIT.java:95)
  at org.elasticsearch.health.node.ShardsCapacityHealthIndicatorServiceIT.testGreen(ShardsCapacityHealthIndicatorServiceIT.java:61)
  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:48)
  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)

```
server/src/internalClusterTest/java/org/elasticsearch/health/node/ShardsCapacityHealthIndicatorServiceIT.java
public void tearDown() throws Exception {
        super.tearDown();
        updateClusterSettings(
            Settings.builder()
                .put(SETTING_CLUSTER_MAX_SHARDS_PER_NODE.getKey(), SETTING_CLUSTER_MAX_SHARDS_PER_NODE.getDefault(Settings.EMPTY))
        );
    }
    public void testGreen() throws Exception {
        
        createIndex(4, 1);
        var result = fetchShardsCapacityIndicatorResult(internalCluster);
        assertEquals(result.status(), HealthStatus.GREEN);
        assertEquals(result.symptom(), "The cluster has enough room to add new shards.");
        assertThat(result.diagnosisList(), empty());
        assertThat(result.impacts(), empty());
    }
    public void testYellow() throws Exception {
        
        createIndex(10, 1);
        var result = fetchShardsCapacityIndicatorResult(internalCluster);
        assertEquals(result.status(), HealthStatus.YELLOW);
        assertEquals(result.symptom(), "Cluster is close to reaching the configured maximum number of shards for data nodes.");
        assertThat(result.diagnosisList(), hasSize(1));
        assertThat(result.impacts(), hasSize(2));
    }
    public void testRed() throws Exception {
        
        createIndex(13, 1);
        var result = fetchShardsCapacityIndicatorResult(internalCluster);
        assertEquals(result.status(), HealthStatus.RED);