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/test/java/org/elasticsearch/cluster/metadata/MetadataTests.java
{
            Map<String, List<AliasMetadata>> aliases = metadata.findAllAliases(new String[] { "index" });
            assertThat(aliases, aMapWithSize(1));
            List<AliasMetadata> aliasMetadataList = aliases.get("index");
            assertThat(aliasMetadataList, transformedItemsMatch(AliasMetadata::alias, contains("alias1", "alias2")));
        }
        {
            Map<String, List<AliasMetadata>> aliases = metadata.findAllAliases(Strings.EMPTY_ARRAY);
            assertThat(aliases, anEmptyMap());
        }
    }
    public void testFindAliasWithExclusion() {
        Metadata metadata = Metadata.builder()
            .put(
                IndexMetadata.builder("index")
                    .settings(Settings.builder().put(IndexMetadata.SETTING_VERSION_CREATED, IndexVersion.current()))
                    .numberOfShards(1)
                    .numberOfReplicas(0)
                    .putAlias(AliasMetadata.builder("alias1").build())
                    .putAlias(AliasMetadata.builder("alias2").build())
            )
            .build();
        GetAliasesRequest request = new GetAliasesRequest().aliases("*", "-alias1");
        List<AliasMetadata> aliases = metadata.findAliases(request.aliases(), new String[] { "index" }).get("index");
        assertThat(aliases, transformedItemsMatch(AliasMetadata::alias, contains("alias2")));
    }
    public void testFindDataStreams() {
        final int numIndices = randomIntBetween(2, 5);
        final int numBackingIndices = randomIntBetween(2, 5);
        final String dataStreamName = "my-data-stream";