Monitoring data export excludes system indices which is not documented

Due to https://github.com/elastic/support-diagnostics/blob/8.1.2/src/main/resources/monitoring-extract/index_stats.json#L5-L11 export of system indices is excluded which is not documented and might be confusing.

The workaround is to remove this section from the query template:
```
"must_not": [
{"wildcard": {
"index_stats.index": {
"value": ".*"
}
}}
],
```