Datanode/opensearch configuration beans

[todvora]

This opensearch configuration handling continues in the direction #21031 started.

The very same configuration handling pattern will be used for Trino.

Benefits of this handling:

• Repeatable configuration builds, groundwork for immutable and read-only configuration
• All configuration options are going through the same pipeline and data types => predictable code and locations instead of chaotic configuration through the whole datanode codebase.
• Configuration can be written to temp directory, for each process run separately and independently (removes existing concurrency issues when restarting opensearch process)
• Massively simplified certificates and security handling
• Unified approach for JVM options, opensearch.yml properties and opensearch.keystore entries
• Password secret completely removed from opensearch configuration, replaced by OTP
• Removes configuration side-effects from opensearch process impl
• Prepared to replace OpensearchConfigSync preflight check (misused to sync default opensearch config files)

/nocl

How Has This Been Tested?

Existing set of unit and integration tests

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Refactoring (non-breaking change)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.