### Elasticsearch Version

master

### Installed Plugins

_No response_

### Java Version

_bundled_

### OS Version

all

### Problem Description

cat indices API in time_series mode is NPE, The reproduce steps is below:

### Steps to Reproduce

```
# step 1
PUT _index_template/test
{
  "index_patterns": [
    "test"
  ],
  "template": {
    "settings": {
      "index.routing_path": "foo"
    },
    "mappings": {
      "properties": {
        "foo": {
          "type": "keyword",
          "time_series_dimension": true
        }
      }
    }
  },
  "data_stream": {
    "index_mode": "time_series"
  }
}

# step 2
PUT _data_stream/test

# step 3
GET _cluster/state/metadata/test
GET _cat/indices/test?v
```
server/src/main/java/org/elasticsearch/cluster/metadata/DataStream.java
}
    /**
     * Determines whether this data stream is replicated from elsewhere,
     * for example a remote cluster.
     *
     * @return Whether this data stream is replicated.
     */
    public boolean isReplicated() {
        return replicated;
    }
    public boolean isSystem() {
        return system;
    }
    public boolean isAllowCustomRouting() {
        return allowCustomRouting;
    }
    @Nullable
    public IndexMode getIndexMode() {
        return indexMode;
    }
    /**
     * Performs a rollover on a {@code DataStream} instance and returns a new instance containing
     * the updated list of backing indices and incremented generation.
     *
     * @param writeIndex            new write index
     * @param generation            new generation
     * @param indexModeFromTemplate the index mode as is defined in the template that created this data stream
     *
     * @return new {@code DataStream} instance with the rollover operation applied
     */