from https://github.com/elastic/kibana/issues/167992

the error `_id must be unset or set to [GvMPW29fWPE5Sr2ZAAABivq9G6A] but was [_id] because [.ds-metrics-logstash.monitoring-default-2023.10.04-000001] is in time_series mode`

No `_id` field is sent as part of the request so the error must be internal to the endpoint functionality.

This is preventing the creation of runtime fields against TSDS data views in kibana.

--

Steps to reproduce via kibana - 
1. Install `Kibana Sample Data Logs (TSDB)` sample data
2. run via dev tools console
```
POST /_scripts/painless/_execute
{
  "script": {
    "source": """
      emit(doc['release_date'].value.year < 1972);
    """
  },
  "context": "boolean_field",
  "context_setup": {
    "index": "kibana_sample_data_logstsdb",
    "document": {
      "name": "Dune",
      "author": "Frank Herbert",
      "release_date": "1965-06-01",
      "page_count": 604,
      "@timestamp" : "2023-09-16T20:06:26.264Z",
      "bytes_counter": 79635479,
      "bytes_gauge": 8823,
      "event": {
        "dataset": "sample_web_logs"
       }
    }
  }
}
```
modules/lang-painless/src/main/java/org/elasticsearch/painless/action/PainlessExecuteAction.java
String[] parts = indexExpression.split(":", 2);
                if (parts.length == 1) {
                    return new Tuple<>(null, parts[0]);
                } else if (parts.length == 2 && parts[1].contains(":") == false) {
                    return new Tuple<>(parts[0], parts[1]);
                } else {
                    throw new IllegalArgumentException(
                        "Unable to parse one single valid index name from the provided index: [" + indexExpression + "]"
                    );
                }
            }
            public String getClusterAlias() {
                return clusterAlias;
            }
            public String getIndex() {
                return index;
            }
            public BytesReference getDocument() {
                return document;
            }
            public QueryBuilder getQuery() {
                return query;
            }
            public XContentType getXContentType() {
                return xContentType;
            }
            public void setXContentType(XContentType xContentType) {
                this.xContentType = xContentType;
            }