### 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/cluster/routing/allocation/ShardsAvailabilityHealthIndicatorService.java
} else {
                
                
                if (clusterShardsPerNodeShouldChange) {
                    diagnosisDefs.add(ACTION_INCREASE_SHARD_LIMIT_CLUSTER_SETTING);
                }
                if (indexShardsPerNodeShouldChange) {
                    diagnosisDefs.add(ACTION_INCREASE_SHARD_LIMIT_INDEX_SETTING);
                }
            }
            return diagnosisDefs;
        } else {
            return List.of();
        }
    }
    private List<Diagnosis.Definition> checkDataTierShouldMigrate(
        IndexMetadata indexMetadata,
        List<NodeAllocationResult> dataTierAllocationResults,
        @Nullable String preferredTier,
        Set<DiscoveryNode> dataTierNodes
    ) {
        
        if (dataTierAllocationResults.stream().allMatch(hasDeciderResult(FilterAllocationDecider.NAME, Decision.Type.NO))) {
            List<Diagnosis.Definition> diagnosisDefs = new ArrayList<>();
            Map<String, List<String>> requireAttributes = INDEX_ROUTING_REQUIRE_GROUP_SETTING.getAsMap(indexMetadata.getSettings());
            List<String> requireDataAttributes = requireAttributes.get("data");
            DiscoveryNodeFilters requireFilter = requireDataAttributes == null
                ? null
                : DiscoveryNodeFilters.buildFromKeyValues(DiscoveryNodeFilters.OpType.AND, Map.of("data", requireDataAttributes));
            Map<String, List<String>> includeAttributes = INDEX_ROUTING_INCLUDE_GROUP_SETTING.getAsMap(indexMetadata.getSettings());