### Description

Elasticsearch defines the concept of a [feature](https://www.elastic.co/guide/en/elasticsearch/reference/current/get-features-api.html) for the purpose of better managing them when snapshotting/restoring them via the [feature_states field](https://www.elastic.co/guide/en/elasticsearch/reference/current/create-snapshot-api.html#create-snapshot-api-feature-states)

The `shards_availability` health indicator currently diagnoses the condition of indices needing to be [restored from a snapshot](https://github.com/elastic/elasticsearch/blob/main/server/src/main/java/org/elasticsearch/cluster/routing/allocation/ShardsAvailabilityHealthIndicatorService.java#L138) and recommends a [troubleshooting guide](http://ela.st/restore-snapshot)

However, since `8.x` the restore API **must** use `feature_states` instead of specifying systems indices or system data streams as part of the `indices` field.

This proposes the `affected_resources` for the `restore_from_snapshot` diagnosis return the indices that are not part of a `feature` under the `INDICES` type, and a new type `FEATURES`.
e.g. instead of current behaviour
```
"affected_resources": {
  "indices": [
    ".geoip_databases",
    "test_index"
    ]
}
```
we could return:
```
"affected_resources": {
  "indices": [
    "test_index"
   ], 
  "features": [
     "geoip"
  ]
}
```



server/src/main/java/org/elasticsearch/node/Node.java
initialEnvironment.pluginsFile()
                );
            }
            deleteTemporaryApmConfig(
                jvmInfo,
                (e, apmConfig) -> logger.error("failed to delete temporary APM config file [{}], reason: [{}]", apmConfig, e.getMessage())
            );
            this.pluginsService = pluginServiceCtor.apply(tmpSettings);
            final Settings settings = mergePluginSettings(pluginsService.pluginMap(), tmpSettings);
            /*
             * Create the environment based on the finalized view of the settings. This is to ensure that components get the same setting
             * values, no matter they ask for them from.
             */
            this.environment = new Environment(settings, initialEnvironment.configFile());
            Environment.assertEquivalent(initialEnvironment, this.environment);
            final List<ExecutorBuilder<?>> executorBuilders = pluginsService.flatMap(p -> p.getExecutorBuilders(settings)).toList();
            final ThreadPool threadPool = new ThreadPool(settings, executorBuilders.toArray(new ExecutorBuilder<?>[0]));
            resourcesToClose.add(() -> ThreadPool.terminate(threadPool, 10, TimeUnit.SECONDS));
            final ResourceWatcherService resourceWatcherService = new ResourceWatcherService(settings, threadPool);
            resourcesToClose.add(resourceWatcherService);
            
            HeaderWarning.setThreadContext(threadPool.getThreadContext());
            resourcesToClose.add(() -> HeaderWarning.removeThreadContext(threadPool.getThreadContext()));
            final Set<String> taskHeaders = Stream.concat(
                pluginsService.filterPlugins(ActionPlugin.class).stream().flatMap(p -> p.getTaskHeaders().stream()),
                Task.HEADERS_TO_COPY.stream()
            ).collect(Collectors.toSet());
            final Tracer tracer = getTracer(pluginsService, settings);
            final TaskManager taskManager = new TaskManager(settings, threadPool, taskHeaders, tracer);