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
* associated with the given index.
     *
     * The passed-in index must already be present in the cluster state, this method cannot
     * be used to add an index.
     *
     * @param index A non-null index
     * @param lifecycleState A non-null lifecycle execution state
     * @return a <code>Metadata</code> instance where the index has the provided lifecycle state
     */
    public Metadata withLifecycleState(final Index index, final LifecycleExecutionState lifecycleState) {
        Objects.requireNonNull(index, "index must not be null");
        Objects.requireNonNull(lifecycleState, "lifecycleState must not be null");
        IndexMetadata indexMetadata = getIndexSafe(index);
        if (lifecycleState.equals(indexMetadata.getLifecycleExecutionState())) {
            return this;
        }
        
        IndexMetadata.Builder indexMetadataBuilder = IndexMetadata.builder(indexMetadata);
        indexMetadataBuilder.version(indexMetadataBuilder.version() + 1);
        indexMetadataBuilder.putCustom(ILM_CUSTOM_METADATA_KEY, lifecycleState.asMap());
        
        final ImmutableOpenMap.Builder<String, IndexMetadata> builder = ImmutableOpenMap.builder(indices);
        builder.put(index.getName(), indexMetadataBuilder.build());
        
        
        
        
        return new Metadata(
            clusterUUID,
            clusterUUIDCommitted,