### 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/test/java/org/elasticsearch/cluster/metadata/MetadataIndexTemplateServiceTests.java
*/
    public void testUpdatingV1NonStarTemplateWithUnchangedPatternsGeneratesWarning() throws Exception {
        final MetadataIndexTemplateService metadataIndexTemplateService = getMetadataIndexTemplateService();
        IndexTemplateMetadata v1Template = IndexTemplateMetadata.builder("v1-template").patterns(Arrays.asList("fo*", "baz")).build();
        ClusterState state = ClusterState.builder(ClusterState.EMPTY_STATE)
            .metadata(Metadata.builder(Metadata.EMPTY_METADATA).put(v1Template).build())
            .build();
        ComposableIndexTemplate v2Template = new ComposableIndexTemplate(
            Arrays.asList("foo-bar-*", "eggplant"),
            null,
            null,
            null,
            null,
            null,
            null,
            null
        );
        state = metadataIndexTemplateService.addIndexTemplateV2(state, false, "v2-template", v2Template);
        assertCriticalWarnings(
            "index template [v2-template] has index patterns [foo-bar-*, eggplant] matching patterns "
                + "from existing older templates [v1-template] with patterns (v1-template => [fo*, baz]); this template [v2-template] will "
                + "take precedence during new index creation"
        );
        assertNotNull(state.metadata().templatesV2().get("v2-template"));
        assertTemplatesEqual(state.metadata().templatesV2().get("v2-template"), v2Template);
        
        MetadataIndexTemplateService.PutRequest req = new MetadataIndexTemplateService.PutRequest("cause", "v1-template");
        req.patterns(Arrays.asList("fo*", "baz"));
        state = MetadataIndexTemplateService.innerPutTemplate(state, req, IndexTemplateMetadata.builder("v1-template"));
        assertCriticalWarnings(