### 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
}
    private static ShardRouting createShardRouting(ShardId shardId, boolean primary, ShardAllocation allocation) {
        var routing = newUnassigned(
            shardId,
            primary,
            getSource(primary, allocation.state),
            new UnassignedInfo(UnassignedInfo.Reason.INDEX_CREATED, null),
            ShardRouting.Role.DEFAULT
        );
        if (allocation.state == INITIALIZING) {
            return routing;
        }
        routing = routing.initialize(allocation.nodeId, null, 0);
        routing = routing.moveToStarted(ShardRouting.UNAVAILABLE_EXPECTED_SHARD_SIZE);
        if (allocation.state == AVAILABLE) {
            return routing;
        }
        if (allocation.state == UNAVAILABLE) {
            return routing.moveToUnassigned(Optional.ofNullable(allocation.unassignedInfo).orElse(randomFrom(nodeLeft(), decidersNo())));
        }
        if (allocation.state == RESTARTING) {
            return routing.moveToUnassigned(
                new UnassignedInfo(
                    UnassignedInfo.Reason.NODE_RESTARTING,
                    null,
                    null,
                    -1,
                    allocation.unassignedTimeNanos != null ? allocation.unassignedTimeNanos : 0,
                    0,
                    false,