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
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));
    }
    private void createIndex(int shards, int replicas) {
        createIndex(INDEX_NAME, Settings.builder().put(SETTING_NUMBER_OF_SHARDS, shards).put(SETTING_NUMBER_OF_REPLICAS, replicas).build());
    }
    private HealthIndicatorResult fetchShardsCapacityIndicatorResult(InternalTestCluster internalCluster) throws Exception {
        var healthNode = findHealthNode().getName();
        var healthService = internalCluster.getInstance(HealthService.class, healthNode);
        var healthIndicatorResults = getHealthServiceResults(healthService, healthNode);
        assertThat(healthIndicatorResults, hasSize(1));
        return healthIndicatorResults.get(0);
    }
    private void setUpCluster(InternalTestCluster internalCluster) throws Exception {
        internalCluster.startMasterOnlyNode();
        internalCluster.startDataOnlyNode();
        internalCluster.startNode(NodeRoles.onlyRole(DATA_FROZEN_NODE_ROLE));
        ensureStableCluster(internalCluster.getNodeNames().length);
        waitForHealthMetadata();
    }
    private List<HealthIndicatorResult> getHealthServiceResults(HealthService healthService, String node) throws Exception {
        AtomicReference<List<HealthIndicatorResult>> resultListReference = new AtomicReference<>();
        ActionListener<List<HealthIndicatorResult>> listener = new ActionListener<>() {
            @Override
            public void onResponse(List<HealthIndicatorResult> healthIndicatorResults) {
                resultListReference.set(healthIndicatorResults);
            }
            @Override
            public void onFailure(Exception e) {