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
* @param indices          the indices to update the number of replicas for
         * @return the builder
         */
        public Builder updateNumberOfReplicas(final int numberOfReplicas, final String[] indices) {
            for (String index : indices) {
                IndexMetadata indexMetadata = this.indices.get(index);
                if (indexMetadata == null) {
                    throw new IndexNotFoundException(index);
                }
                put(IndexMetadata.builder(indexMetadata).numberOfReplicas(numberOfReplicas));
            }
            return this;
        }
        public Builder coordinationMetadata(CoordinationMetadata coordinationMetadata) {
            this.coordinationMetadata = coordinationMetadata;
            return this;
        }
        public Settings transientSettings() {
            return this.transientSettings;
        }
        public Builder transientSettings(Settings settings) {
            this.transientSettings = settings;
            return this;
        }
        public Settings persistentSettings() {
            return this.persistentSettings;
        }
        public Builder persistentSettings(Settings settings) {
            this.persistentSettings = settings;
            return this;