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
},      "properties": {
                "name": {
                  "properties": {
                    "first": {
                      "type": "keyword"
                    },
                    "last": {
                      "type": "keyword"
                    }
                  }
                },
                "birth": {
                  "type": "date"
                },
                "age": {
                  "type": "integer"
                },
                "ip": {
                  "type": "ip"
                },
                "suggest" : {
                  "type": "completion"
                },
                "address": {
                  "type": "object",
                  "properties": {
                    "street": {
                      "type": "keyword"
                    },
                    "location": {