### 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
import org.elasticsearch.test.ESTestCase;
import org.elasticsearch.threadpool.ThreadPool;
import org.mockito.stubbing.Answer;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import java.util.Set;
import java.util.UUID;
import java.util.stream.Collectors;
import static java.util.Collections.emptyList;
import static java.util.stream.Collectors.toMap;
import static org.elasticsearch.cluster.metadata.DataStreamTestHelper.createBackingIndex;
import static org.elasticsearch.cluster.metadata.DataStreamTestHelper.newInstance;
import static org.elasticsearch.cluster.metadata.IndexMetadata.INDEX_ROUTING_INCLUDE_GROUP_PREFIX;
import static org.elasticsearch.cluster.metadata.IndexMetadata.INDEX_ROUTING_REQUIRE_GROUP_PREFIX;
import static org.elasticsearch.cluster.metadata.SingleNodeShutdownMetadata.Type.RESTART;
import static org.elasticsearch.cluster.routing.ShardRouting.newUnassigned;
import static org.elasticsearch.cluster.routing.allocation.ShardsAvailabilityHealthIndicatorService.ACTION_CHECK_ALLOCATION_EXPLAIN_API;
import static org.elasticsearch.cluster.routing.allocation.ShardsAvailabilityHealthIndicatorService.ACTION_ENABLE_CLUSTER_ROUTING_ALLOCATION;
import static org.elasticsearch.cluster.routing.allocation.ShardsAvailabilityHealthIndicatorService.ACTION_ENABLE_INDEX_ROUTING_ALLOCATION;
import static org.elasticsearch.cluster.routing.allocation.ShardsAvailabilityHealthIndicatorService.ACTION_ENABLE_TIERS_LOOKUP;
import static org.elasticsearch.cluster.routing.allocation.ShardsAvailabilityHealthIndicatorService.ACTION_INCREASE_NODE_CAPACITY;
import static org.elasticsearch.cluster.routing.allocation.ShardsAvailabilityHealthIndicatorService.ACTION_INCREASE_SHARD_LIMIT_CLUSTER_SETTING;
import static org.elasticsearch.cluster.routing.allocation.ShardsAvailabilityHealthIndicatorService.ACTION_INCREASE_SHARD_LIMIT_CLUSTER_SETTING_LOOKUP;
import static org.elasticsearch.cluster.routing.allocation.ShardsAvailabilityHealthIndicatorService.ACTION_INCREASE_SHARD_LIMIT_INDEX_SETTING;
import static org.elasticsearch.cluster.routing.allocation.ShardsAvailabilityHealthIndicatorService.ACTION_INCREASE_SHARD_LIMIT_INDEX_SETTING_LOOKUP;
import static org.elasticsearch.cluster.routing.allocation.ShardsAvailabilityHealthIndicatorService.ACTION_INCREASE_TIER_CAPACITY_LOOKUP;