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
private static final TransportVersion NOOP_METADATA_DIFF_VERSION = TransportVersion.V_8_5_0;
        private static final TransportVersion NOOP_METADATA_DIFF_SAFE_VERSION =
            PublicationTransportHandler.INCLUDES_LAST_COMMITTED_DATA_VERSION;
        private final long version;
        private final String clusterUUID;
        private final boolean clusterUUIDCommitted;
        private final CoordinationMetadata coordinationMetadata;
        private final Settings transientSettings;
        private final Settings persistentSettings;