Change the mechanism to enable LogsDB

[salvatore-campagna]

Description

With PR #109025 we introduced a mechanism relying on component templates
to enable LogsDB. This mechanism uses a static setting and despite being useful to enable LogsDB for new deployments
it makes it difficult to do so for existing deployments. Moreover, changing component templates
like logs@settings requires bumping the stack template registry version. As a result, enabling LogsDB requires pushing
a change and redeploying. This makes LogsDB activation quite involved.

We decided to introduce a new mechanism that makes enabling LogsDB easier and that does not rely on templates
and/or component templates. We can use the existing IndexSettingProvider functionality to evaluate a cluster setting
cluster.logsdb.enabled at index creation time and, under certain conditions, inject the index.mode setting with value
logsdb.

[elasticsearchmachine]

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