### 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/test/java/org/elasticsearch/cluster/routing/allocation/ShardsAvailabilityHealthIndicatorServiceTests.java
List<Diagnosis.Definition> actions = service.checkDataTierRelatedIssues(
            indexMetadata,
            List.of(
                
                new NodeAllocationResult(
                    new DiscoveryNode(
                        randomNodeId(),
                        buildNewFakeTransportAddress(),
                        Map.of(),
                        Set.of(DiscoveryNodeRole.DATA_ROLE),
                        Version.CURRENT
                    ),
                    new Decision.Multi().add(Decision.single(Decision.Type.YES, "data_tier", null))
                        .add(Decision.single(Decision.Type.NO, SameShardAllocationDecider.NAME, null)),
                    1
                )
            ),
            ClusterState.EMPTY_STATE
        );
        assertThat(actions, hasSize(1));
        assertThat(actions, contains(ACTION_INCREASE_NODE_CAPACITY));
    }
    public void testLimitNumberOfAffectedResources() {
        var clusterState = createClusterStateWith(
            List.of(
                index("red-index1", new ShardAllocation(randomNodeId(), UNAVAILABLE), new ShardAllocation(randomNodeId(), AVAILABLE)),
                index("red-index2", new ShardAllocation(randomNodeId(), UNAVAILABLE), new ShardAllocation(randomNodeId(), AVAILABLE)),
                index("red-index3", new ShardAllocation(randomNodeId(), UNAVAILABLE), new ShardAllocation(randomNodeId(), AVAILABLE)),
                index("red-index4", new ShardAllocation(randomNodeId(), UNAVAILABLE), new ShardAllocation(randomNodeId(), AVAILABLE)),
                index("red-index5", new ShardAllocation(randomNodeId(), UNAVAILABLE), new ShardAllocation(randomNodeId(), AVAILABLE))