Change database.enabled to default to "prefer"

Summary

Update the Container Registry's default database.enabled configuration to "prefer" as outlined in Epic &19638.

Background

With the new string-based database.enabled configuration supporting "prefer mode", the Container Registry should default to "prefer" to enable fresh installations to automatically use the metadata database while preserving existing deployments' behavior.

Implementation

Update the Container Registry's configuration defaults:

• Change the default value of database.enabled from false to "prefer"

Success Criteria

• Container Registry defaults database.enabled to "prefer"
• Fresh installs with no previous metadata automatically use database metadata
• Existing installs continue with their current metadata method