Enable LogsDB by default for `logs-*-*` for Serverless deployments

[salvatore-campagna]

Description

For Serverless deployments we would like to control enabling LogsDB in such a way that we can introduce it independently from what we do for non-Serverless deployments (as explained by issue #106489).

PR #109025 introduces a setting that we can change in the Serverless project to enable LogsDB just for Serverless deployments, giving us the ability to turn on usage of LogsDB for logs-*-* whenever required.

At the moment of creating this issue the idea is to take advantage of release 9.0 to introduce LogsDB in Servrless (taking advantage of the major release).

[elasticsearchmachine]

Pinging @elastic/es-storage-engine (Team:StorageEngine)