### Elasticsearch Version

8.4, 8.5, 8.6

### Installed Plugins

_No response_

### Java Version

_bundled_

### OS Version

Darwin

### Problem Description

The shards availability indicator should always be reporting diagnosis when its status is RED/YELLOW.
However, when an index is on a data node that runs out of disk space it will report RED but no diagnosis.

### Steps to Reproduce

Have multi-node cluster where a data (non-master) node that hosts an index runs out of disk space (the index cannot relocate somewhere else).
Call the Health API and the output will be something along these lines:
```
    "shards_availability": {
      "status": "red",
      "symptom": "This cluster has all shards available.",
      "details": {
        "initializing_primaries": 1,
        "started_replicas": 0,
        "initializing_replicas": 0,
        "unassigned_primaries": 0,
        "started_primaries": 1,
        "creating_primaries": 0,
        "unassigned_replicas": 0,
        "restarting_primaries": 0,
        "restarting_replicas": 0
      },
      "impacts": [
        {
          "id": "elasticsearch:health:shards_availability:impact:primary_unassigned",
          "severity": 1,
          "description": "Cannot add data to 1 index [test_index]. Searches might return incomplete results.",
          "impact_areas": [
            "ingest",
            "search"
          ]
        }
      ] 
    }
``` 

### Logs (if relevant)

_No response_
server/src/test/java/org/elasticsearch/cluster/routing/allocation/ShardsAvailabilityHealthIndicatorServiceTests.java
)
                )
        );
        Metadata.Builder metadataBuilder = Metadata.builder();
        Map<String, IndexMetadata> indexMetadataMap = new HashMap<>();
        for (IndexMetadata indexMetadata : indexMetadataList) {
            indexMetadataMap.put(indexMetadata.getIndex().getName(), indexMetadata);
        }
        metadataBuilder.indices(indexMetadataMap);
        metadataBuilder.putCustom(NodesShutdownMetadata.TYPE, nodesShutdownMetadata);
        DiscoveryNodes.Builder discoveryNodesBuilder = DiscoveryNodes.builder();
        nodes.forEach(discoveryNodesBuilder::add);
        return ClusterState.builder(new ClusterName("test-cluster"))
            .routingTable(routingTableBuilder.build())
            .nodes(discoveryNodesBuilder)
            .metadata(metadataBuilder.build())
            .build();
    }
    private static Map<String, Object> addDefaults(Map<String, Object> override) {
        return Map.of(
            "unassigned_primaries",
            override.getOrDefault("unassigned_primaries", 0),
            "initializing_primaries",
            override.getOrDefault("initializing_primaries", 0),
            "creating_primaries",
            override.getOrDefault("creating_primaries", 0),
            "restarting_primaries",
            override.getOrDefault("restarting_primaries", 0),
            "started_primaries",
            override.getOrDefault("started_primaries", 0),