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
import org.apache.logging.log4j.Logger;
import org.apache.lucene.util.CollectionUtil;
import org.elasticsearch.TransportVersion;
import org.elasticsearch.cluster.ClusterState;
import org.elasticsearch.cluster.Diff;
import org.elasticsearch.cluster.Diffable;
import org.elasticsearch.cluster.DiffableUtils;
import org.elasticsearch.cluster.NamedDiffable;
import org.elasticsearch.cluster.NamedDiffableValueSerializer;
import org.elasticsearch.cluster.SimpleDiffable;
import org.elasticsearch.cluster.block.ClusterBlock;
import org.elasticsearch.cluster.block.ClusterBlockLevel;
import org.elasticsearch.cluster.coordination.CoordinationMetadata;
import org.elasticsearch.cluster.coordination.PublicationTransportHandler;
import org.elasticsearch.cluster.metadata.IndexAbstraction.ConcreteIndex;
import org.elasticsearch.cluster.routing.RoutingTable;
import org.elasticsearch.common.Strings;
import org.elasticsearch.common.UUIDs;
import org.elasticsearch.common.collect.ImmutableOpenMap;
import org.elasticsearch.common.collect.Iterators;
import org.elasticsearch.common.io.stream.StreamInput;
import org.elasticsearch.common.io.stream.StreamOutput;
import org.elasticsearch.common.io.stream.VersionedNamedWriteable;
import org.elasticsearch.common.regex.Regex;
import org.elasticsearch.common.settings.Setting;
import org.elasticsearch.common.settings.Setting.Property;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.common.util.ArrayUtils;
import org.elasticsearch.common.util.Maps;
import org.elasticsearch.common.util.set.Sets;