#3407 feat: Set `Stream.replication_key` in metadata as the default replication key Pull request opened by edgarrmondragon ## Summary by Sourcery Set the catalog’s standard metadata to populate the root replication key when exactly one valid replication key is provided. Bug Fixes: • Ensure the root metadata replication key is left unset when there are zero or multiple valid replication keys. Tests: • Add coverage to verify default replication key behavior in standard metadata for zero, one, and multiple valid replication keys. meltano/sdk