A composable index template with no `template` defined in the body is mistakingly always assumed to not be a time series template. Even if it refers to a component template that has the `index.mode` setting set to `time_series` and the component template defines mappings with dimension fields or routing paths.

Incorrectly this causes to create a data stream with a tsdb index *without* time series start and end time settings set. The fact that this can happen is another bug and is being tracked #98833.

What should happen in this case is that a tsdb data stream is created with a valid tsdb backing index (with correctly generated time series start and end time settings).

This bug was found as part investigating #98792 and is the cause of that bug.
server/src/main/java/org/elasticsearch/cluster/metadata/Metadata.java
}
    public Map<String, ComposableIndexTemplate> templatesV2() {
        return Optional.ofNullable((ComposableIndexTemplateMetadata) this.custom(ComposableIndexTemplateMetadata.TYPE))
            .map(ComposableIndexTemplateMetadata::indexTemplates)
            .orElse(Collections.emptyMap());
    }
    public boolean isTimeSeriesTemplate(ComposableIndexTemplate indexTemplate) {
        var template = indexTemplate.template();
        if (indexTemplate.getDataStreamTemplate() == null || template == null) {
            return false;
        }
        var settings = MetadataIndexTemplateService.resolveSettings(indexTemplate, componentTemplates());
        
        var rawIndexMode = settings.get(IndexSettings.MODE.getKey());
        var indexMode = rawIndexMode != null ? Enum.valueOf(IndexMode.class, rawIndexMode.toUpperCase(Locale.ROOT)) : null;
        if (indexMode == IndexMode.TIME_SERIES) {
            
            
            
            
            return true;
        }
        
        
        return false;
    }
    public Map<String, DataStream> dataStreams() {
        return this.custom(DataStreamMetadata.TYPE, DataStreamMetadata.EMPTY).dataStreams();
    }
    public Map<String, DataStreamAlias> dataStreamAliases() {