[cleanup][ml] Remove unused metadata quorum configuration fields

[somiljain2006]

Fixes #26212

Motivation

The metadataEnsembleSize, metadataWriteQuorumSize, and metadataAckQuorumSize fields in ManagedLedgerConfig are non-functional dead code resulting from a 2018 regression. Calls to their setters in BrokerService and ManagedLedgerWriter are silently ignored because their getters are never called in production, misleading users who attempt to configure separate ensemble settings for cursor ledgers. Removing these fields cleans up technical debt without impacting functionality.

Modifications

Removed metadataEnsembleSize, metadataWriteQuorumSize, and metadataAckQuorumSize alongside their getter/setter methods in ManagedLedgerConfig.java, and stripped all corresponding setter invocations from BrokerService.java, ManagedLedgerWriter.java, and affected unit test classes.

Verifying this change

• Make sure that the change passes the CI checks.

This change is a trivial rework/code cleanup without any test coverage.

Does this pull request potentially affect one of the following parts:

If the box was checked, please highlight the changes

• Dependencies (add or upgrade a dependency)
• The public API
• The schema
• The default values of configurations
• The threading model
• The binary protocol
• The REST endpoints
• The admin CLI options
• The metrics
• Anything that affects deployment

[lhotari]

LGTM