### Elasticsearch Version

8.7+

### Installed Plugins

_No response_

### Java Version

_bundled_

### OS Version

Darwin

### Problem Description

The downsample transport action ( https://github.com/elastic/elasticsearch/blob/main/x-pack/plugin/rollup/src/main/java/org/elasticsearch/xpack/downsample/TransportDownsampleAction.java ) creates a rollup index without setting any tier preference.

This means the rollup index will receive the automatic tier preference of `data_content` irrespective of where the source index is located.
This means that even if the source index is in the warm tier, the rollup index will be created in the hot tier (so we'd be downsampling from warm to hot).

This has some confusing consequences when using ILM if, say,  the `downsample` action is configured in the `cold` phase the hot tier could run out of space (or at least see increased, unexpected (?) usage)

Maybe this makes sense for performance reasons? If that's the case I think we should document this behaviour.
We should otherwise configure the `_tier_preference` on the rollup index.

### Steps to Reproduce

Spin up a deployment with hot/warm/cold tiers.
Create an index with the `_tier_preference: data_warm` and create an ILM policy with only the warm phase that contains the `downsample` action ( https://www.elastic.co/guide/en/elasticsearch/reference/current/downsampling-ilm.html )
Notice the `downsample-*` index is created in the hot tier.


### Logs (if relevant)

_No response_
x-pack/plugin/rollup/src/main/java/org/elasticsearch/xpack/downsample/TransportDownsampleAction.java
public void onResponse(AcknowledgedResponse acknowledgedResponse) {
                if (e == null && acknowledgedResponse.isAcknowledged()) {
                    listener.onResponse(acknowledgedResponse);
                } else {
                    listener.onFailure(new ElasticsearchException("Unable to rollup index [" + sourceIndex + "]", e));
                }
            }
            @Override
            public void onFailure(Exception deleteException) {
                listener.onFailure(new ElasticsearchException("Unable to delete rollup index [" + rollupIndex + "]", e));
            }
        });
    }
    /**
     * A specialized cluster state update task that always takes a listener handling an
     * AcknowledgedResponse, as all template actions have simple acknowledged yes/no responses.
     */
    private abstract static class RollupClusterStateUpdateTask implements ClusterStateTaskListener {
        final ActionListener<AcknowledgedResponse> listener;
        RollupClusterStateUpdateTask(ActionListener<AcknowledgedResponse> listener) {
            this.listener = listener;
        }
        public abstract ClusterState execute(ClusterState currentState) throws Exception;
        @Override
        public void onFailure(Exception e) {
            listener.onFailure(e);
        }
    }
}