Introduce new node feature for renaming health endpoint (#107154)

The health API was available for experimentation under the
[`_internal/_health`](https://www.elastic.co/guide/en/elasticsearch/reference/8.6/health-api.html)
before it [became
GA](https://www.elastic.co/guide/en/elasticsearch/reference/8.7/health-api.html)
at `8.7.0`. For this reason we introduce another node feature to capture
this change.

Fixes #106933

Author: gmarouli

qa/rolling-upgrade/src/javaRestTest/java/org/elasticsearch/upgrades/HealthNodeUpgradeIT.java

@@ -11,7 +11,6 @@
 import com.carrotsearch.randomizedtesting.annotations.Name;
 
 import org.apache.http.util.EntityUtils;
-import org.apache.lucene.tests.util.LuceneTestCase.AwaitsFix;
 import org.elasticsearch.client.Request;
 import org.elasticsearch.client.Response;
 import org.hamcrest.Matchers;
@@ -21,7 +20,6 @@
 
 import static org.hamcrest.CoreMatchers.equalTo;
 
-@AwaitsFix(bugUrl = "https://github.com/elastic/elasticsearch/issues/106933")
 public class HealthNodeUpgradeIT extends ParameterizedRollingUpgradeTestCase {
 
     public HealthNodeUpgradeIT(@Name("upgradedNodes") int upgradedNodes) {
@@ -36,7 +34,8 @@ public void testHealthNode() throws Exception {
                 assertThat(tasks, Matchers.containsString("health-node"));
             });
             assertBusy(() -> {
-                Response response = client().performRequest(new Request("GET", "_health_report"));
+                String path = clusterHasFeature("health.supports_health_report_api") ? "_health_report" : "_internal/_health";
+                Response response = client().performRequest(new Request("GET", path));
                 Map<String, Object> health_report = entityAsMap(response.getEntity());
                 assertThat(health_report.get("status"), equalTo("green"));
             });

server/src/main/java/org/elasticsearch/health/HealthFeatures.java

@@ -18,6 +18,7 @@
 public class HealthFeatures implements FeatureSpecification {
 
     public static final NodeFeature SUPPORTS_HEALTH = new NodeFeature("health.supports_health");
+    public static final NodeFeature SUPPORTS_HEALTH_REPORT_API = new NodeFeature("health.supports_health_report_api");
     public static final NodeFeature SUPPORTS_SHARDS_CAPACITY_INDICATOR = new NodeFeature("health.shards_capacity_indicator");
     public static final NodeFeature SUPPORTS_EXTENDED_REPOSITORY_INDICATOR = new NodeFeature("health.extended_repository_indicator");
 
@@ -28,6 +29,13 @@ public Set<NodeFeature> getFeatures() {
 
     @Override
     public Map<NodeFeature, Version> getHistoricalFeatures() {
-        return Map.of(SUPPORTS_HEALTH, Version.V_8_5_0, SUPPORTS_SHARDS_CAPACITY_INDICATOR, Version.V_8_8_0);
+        return Map.of(
+            SUPPORTS_HEALTH,
+            Version.V_8_5_0,                // health accessible via /_internal/_health
+            SUPPORTS_HEALTH_REPORT_API,
+            Version.V_8_7_0,                // health accessible via /_health_report
+            SUPPORTS_SHARDS_CAPACITY_INDICATOR,
+            Version.V_8_8_0
+        );
     }
 }