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 Metadata withLastCommittedValues(
        boolean clusterUUIDCommitted,
        CoordinationMetadata.VotingConfiguration lastCommittedConfiguration
    ) {
        if (clusterUUIDCommitted == this.clusterUUIDCommitted
            && lastCommittedConfiguration.equals(this.coordinationMetadata.getLastCommittedConfiguration())) {
            return this;
        }
        return new Metadata(
            clusterUUID,
            clusterUUIDCommitted,
            version,
            CoordinationMetadata.builder(coordinationMetadata).lastCommittedConfiguration(lastCommittedConfiguration).build(),
            transientSettings,
            persistentSettings,
            settings,
            hashesOfConsistentSettings,
            totalNumberOfShards,
            totalOpenIndexShards,
            indices,
            aliasedIndices,
            templates,
            customs,
            allIndices,
            visibleIndices,
            allOpenIndices,
            visibleOpenIndices,
            allClosedIndices,
            visibleClosedIndices,
            indicesLookup,