fix: align private-cloud Oxia example

[mattisonchao]

Motivation

• Align the private-cloud Oxia example with the Oxia metadata layout from the charts changes.
• Include the Oxia namespaces needed for broker, BookKeeper, function state, and schema/system-topic storage.

Modifications

• Update the Oxia image to oxia/oxia:0.16.7.
• Add function and pulsar-schema OxiaNamespace resources.
• Set all Oxia namespaces to initialShardCount: 1, replicationFactor: 3, notificationsEnabled: true, and ownerRef to the PulsarBroker.
• Use FQDN Oxia service URLs for BookKeeper and broker metadata.
• Enable oxiaBasedSystemTopic for schema and topic policy storage while relying on operator-generated metadata/package-management config.

Testing

• Parsed oxia/pulsar-oxia.yaml with Ruby YAML loader.
• Verified the manifest has 9 documents, 4 OxiaNamespace resources, all namespace initialShardCount values set to 1, and Oxia image oxia/oxia:0.16.7.
• Ran git diff --check HEAD~1 HEAD.