Data stream should exclude elastic built-in ones in telemetry

Description

Today, data stream telemetry shows all data streams in the cluster:

### From GET _xpack/usage
"data_streams" : {
    "available" : true,
    "enabled" : true,
    "data_streams" : 4,
    "indices_count" : 4
},

However, many of them are built-in from Elastic or the connected products like:

.ds-.logs-deprecation.elasticsearch-default
.ds-ilm-history-5
.ds-.logs-enterprise_search.api-default ...

Thus, it's not easy to know the real adoption of data stream. Is it possible to exclude certain indices from _xpack/usage when counting data_streams.indices_count? Or just have another field called data.streams.system_indices_count?

elastic / elasticsearch

Data stream should exclude elastic built-in ones in telemetry #86258

Description