### Elasticsearch Version

7.x, 8.x

### Installed Plugins

_No response_

### Java Version

_bundled_

### OS Version

Darwin 

### Problem Description

A data stream must have an index template that matches it in order to exist.
When managing index templates we want to make sure we don't leave a
data stream without a [corresponding index template](https://github.com/elastic/elasticsearch/blob/acf9968f9d397d755d5ad9fcf815cca23bbeda61/server/src/main/java/org/elasticsearch/cluster/metadata/MetadataIndexTemplateService.java#L918).

The `dataStreamsUsingTemplate` check uses the index pattern of the index 
templates to conclude if a template is used by a data stream, however it should
be enhanced to check the priority too as there can only be only one index template
that matches a data stream and it's the one with the highest priority.

### Steps to Reproduce

Create an ILM policy
```
PUT _ilm/policy/testing_yo
{
  "policy": {
    "phases": {
      "warm": {
	"actions": {
	  "shrink": {
          "number_of_shards": 1
	  }
        }
      }
    } 
  }
}
```

Create an index template with the `data_stream` option:
```
PUT _index_template/logs_data_stream
{
	"index_patterns": [ "logs*", "te*", "bar*" ],
	"data_stream": {},
        "priority": 100,
	"template" : {
	  "settings": {
            "index.number_of_shards": 3,
	    "index.lifecycle.name": "testing"
	  }
	}
}
```

Create the data stream
```
POST logs_test/_doc 
{
  "message": "testing",
  "@timestamp": "1591890611"
}
```

Create a new index template that would match this data stream with a higher priority
```
PUT _index_template/higher_logs_data_stream
{
	"index_patterns": [ "logs*", "te*", "bar*" ],
	"data_stream": {},
        "priority": 500,
	"template" : {
	  "settings": {
            "index.number_of_shards": 3,
	    "index.lifecycle.name": "testing"
	  }
	}
}
```

Attempt to delete the previous, lower priority index template:
```
DELETE _index_template/logs_data_stream
```

### Logs (if relevant)

_No response_
server/src/main/java/org/elasticsearch/cluster/metadata/MetadataIndexTemplateService.java
final List<ComposableIndexTemplate> candidates = new ArrayList<>(matchedTemplates.keySet());
        CollectionUtil.timSort(candidates, Comparator.comparing(ComposableIndexTemplate::priorityOrZero, Comparator.reverseOrder()));
        assert candidates.size() > 0 : "we should have returned early with no candidates";
        ComposableIndexTemplate winner = candidates.get(0);
        String winnerName = matchedTemplates.get(winner);
        
        
        
        
        if (winner.indexPatterns().stream().anyMatch(Regex::isMatchAllPattern)
            && IndexMetadata.INDEX_HIDDEN_SETTING.exists(resolveSettings(metadata, winnerName))) {
            throw new IllegalStateException(
                "global index template ["
                    + winnerName
                    + "], composed of component templates ["
                    + String.join(",", winner.composedOf())
                    + "] defined the index.hidden setting, which is not allowed"
            );
        }
        return winnerName;
    }
    /**
     * Collect the given v2 template into an ordered list of mappings.
     */
    public static List<CompressedXContent> collectMappings(final ClusterState state, final String templateName, final String indexName)
        throws Exception {
        final ComposableIndexTemplate template = state.metadata().templatesV2().get(templateName);
        assert template != null
            : "attempted to resolve mappings for a template [" + templateName + "] that did not exist in the cluster state";
        if (template == null) {