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
* @throws IndexNotFoundException if no metadata for this index is found
     */
    public IndexMetadata getIndexSafe(Index index) {
        IndexMetadata metadata = index(index.getName());
        if (metadata != null) {
            if (metadata.getIndexUUID().equals(index.getUUID())) {
                return metadata;
            }
            throw new IndexNotFoundException(
                index,
                new IllegalStateException(
                    "index uuid doesn't match expected: [" + index.getUUID() + "] but got: [" + metadata.getIndexUUID() + "]"
                )
            );
        }
        throw new IndexNotFoundException(index);
    }
    public Map<String, IndexMetadata> indices() {
        return this.indices;
    }
    public Map<String, IndexMetadata> getIndices() {
        return indices();
    }
    /**
     * Returns whether an alias exists with provided alias name.
     *
     * @param aliasName The provided alias name
     * @return whether an alias exists with provided alias name
     */
    public boolean hasAlias(String aliasName) {