[@kbn/es] Improve CI stats reporting on docker and serverless commands in FTR

[mistic]

The execa promise only resolves if we run docker detached, which loses automatic log outputs to the users. Because of that there is not good way right now to report metrics like ready for those commands.

It's possible that we find out a way to do this differently and open that possibility (for example communicating the logs back through a socket and log those through the main process or use that strategy to report the metrics itself)

[elasticmachine]

Pinging @elastic/kibana-operations (Team:Operations)

[Ikuni17]

I think we might be able to achieve this by running docker logs -f <containerId / containerName> after we start the detached containers.

[Ikuni17]

@mistic There have been a few instances where having these logs available would have helped debug difficult or obscure test failures with ES serverless. wdyt about increasing the priority?

[Ikuni17]

The logging aspect of this issue has been handled by #189231