Skip HealthNodeUpgradeIT for some rolling upgrades (#119698)

* Skip HealthNodeUpgradeIT for some rolling upgrades

This skips part of the `HealthNodeUpgradeIT` test for the rolling
upgrade tests which use a cluster with a mix of 8.5.x and 8.6.x nodes,
which serve the health endpoint at `_internal/_health`, and 8.last
nodes, which serve it at `_health_report`. There is no sensible and
reliable way to test the endpoint in such clusters.

Closes #118157
Closes #118158

Author: PeteGillinElastic

muted-tests.yml

@@ -378,12 +378,6 @@ tests:
 - class: org.elasticsearch.xpack.esql.action.EsqlActionTaskIT
   method: testCancelRequestWhenFailingFetchingPages
   issue: https://github.com/elastic/elasticsearch/issues/118213
-- class: org.elasticsearch.upgrades.HealthNodeUpgradeIT
-  method: testHealthNode {upgradedNodes=1}
-  issue: https://github.com/elastic/elasticsearch/issues/118157
-- class: org.elasticsearch.upgrades.HealthNodeUpgradeIT
-  method: testHealthNode {upgradedNodes=2}
-  issue: https://github.com/elastic/elasticsearch/issues/118158
 - class: org.elasticsearch.xpack.inference.DefaultEndPointsIT
   method: testInferDeploysDefaultRerank
   issue: https://github.com/elastic/elasticsearch/issues/118184

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

@@ -28,15 +28,21 @@ public HealthNodeUpgradeIT(@Name("upgradedNodes") int upgradedNodes) {
     }
 
     public void testHealthNode() throws Exception {
+        // Assert that the response from _cat/tasks returns health-node provided the health.supports_health feature is present
         if (clusterHasFeature("health.supports_health")) {
             assertBusy(() -> {
                 Response response = client().performRequest(new Request("GET", "_cat/tasks"));
                 String tasks = EntityUtils.toString(response.getEntity(), StandardCharsets.UTF_8);
                 assertThat(tasks, Matchers.containsString("health-node"));
             });
+        }
+
+        // Assert that _health_report endpoint returns a green status provided the health.supports_health_report_api feature is present
+        // N.B. If this feature is not present, the cluster may have a mixture of nodes which serve the health endpoint at /_health_report
+        // and older nodes which serve it at /_internal/_health. There is no sensible and reliable way to test the endpoint in this case.
+        if (clusterHasFeature("health.supports_health_report_api")) {
             assertBusy(() -> {
-                String path = clusterHasFeature("health.supports_health_report_api") ? "_health_report" : "_internal/_health";
-                Response response = client().performRequest(new Request("GET", path));
+                Response response = client().performRequest(new Request("GET", "_health_report"));
                 Map<String, Object> health_report = entityAsMap(response.getEntity());
                 assertThat(health_report.get("status"), equalTo("green"));
             });