* Merge test runner task into RestIntegTest (#60261)
* Merge test runner task into RestIntegTest
* Reorganizing Standalone runner and RestIntegTest task
* Rework general test task configuration and extension
* Fix merge issues
* use former 7.x common test configuration
This commit adds data stream info to the `/_xpack` and `/_xpack/usage` APIs. Currently the usage is
pretty minimal, returning only the number of data streams and the number of indices currently
abstracted by a data stream:
```
...
"data_streams" : {
"available" : true,
"enabled" : true,
"data_streams" : 3,
"indices_count" : 17
}
...
```