Currently, shardsvrCommitToShardLocalCatalog combines multiple responsibilities. To improve clarity and maintainability, we should split this command into separate _shardsvrCommitCreateDatabase and _shardsvrCommitDropDatabase commands, for example.

Additionally, consider refactoring the ShardServerOpObserver logic to avoid unnecessary serialization and deserialization. Introducing separate onDatabaseMetadataUpdate methods for each sharding catalog DDL operation may be beneficial, even if it increases the number of methods in OpObserver.