Refactor test with different disconnect code

Author: smalyshev

test/framework/src/main/java/org/elasticsearch/test/AbstractMultiClustersTestCase.java

@@ -264,15 +264,6 @@ public void close() throws IOException {
         }
     }
 
-    protected void removeClusterFromGroup(String clusterAlias) {
-        clusterGroup = new ClusterGroup(
-            clusterGroup.clusters.entrySet()
-                .stream()
-                .filter(e -> e.getKey().equals(clusterAlias) == false)
-                .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue))
-        );
-    }
-
     static NodeConfigurationSource nodeConfigurationSource(Settings nodeSettings, Collection<Class<? extends Plugin>> nodePlugins) {
         final Settings.Builder builder = Settings.builder();
         builder.putList(DISCOVERY_SEED_HOSTS_SETTING.getKey()); // empty list disables a port scan for other nodes

x-pack/plugin/esql/src/internalClusterTest/java/org/elasticsearch/xpack/esql/action/CrossClusterCancellationIT.java

@@ -304,9 +304,11 @@ public void testCloseSkipUnavailable() throws Exception {
         request.pragmas(randomPragmas());
         var requestFuture = client().execute(EsqlQueryAction.INSTANCE, request);
         assertTrue(SimplePauseFieldPlugin.startEmitting.await(30, TimeUnit.SECONDS));
+        // Disconnect the remotes
+        for (var transportService : cluster(LOCAL_CLUSTER).getInstances(TransportService.class)) {
+            transportService.getRemoteClusterService().getRemoteClusterConnection(REMOTE_CLUSTER).close();
+        }
         SimplePauseFieldPlugin.allowEmitting.countDown();
-        cluster(REMOTE_CLUSTER).close();
-        removeClusterFromGroup(REMOTE_CLUSTER);
         try (var resp = requestFuture.actionGet()) {
             EsqlExecutionInfo executionInfo = resp.getExecutionInfo();
             assertNotNull(executionInfo);