Backport to branch(3) : Add configuration option to enable/disable active transaction management

[feeblefakie]

This is an automated backport of the following:

• Original PR: Add configuration option to enable/disable active transaction management #3233
• Backported commit: ca1cfb6

Please merge this PR after all checks have passed.

[gemini-code-assist]

Summary of Changes

Hello @feeblefakie, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request introduces a new configuration setting that provides granular control over whether active transaction management is enabled within the system. This change is accompanied by a significant refactoring effort, which centralizes the application of transaction management wrappers into a new abstract provider. Furthermore, the core mechanism for tracking and expiring active transactions has been encapsulated into a dedicated registry, improving code organization and maintainability. These updates also include enhancements to ensure thread safety for scanner operations, addressing potential concurrency issues.

Highlights

• Configurable Active Transaction Management: Introduced a new configuration option active_transaction_management.enabled in DatabaseConfig to allow users to enable or disable the active transaction management feature.
• Centralized Transaction Provider Logic: Extracted and centralized the logic for wrapping DistributedTransactionManager and TwoPhaseCommitTransactionManager with state and active transaction management into a new AbstractDistributedTransactionProvider class.
• Dedicated Active Transaction Registry: Created a new ActiveTransactionRegistry class to encapsulate the ActiveExpiringMap and its associated logic for managing active transactions, including their expiration and rollback, promoting better modularity.
• Enhanced Scanner Thread Safety: Implemented a SynchronizedScanner class to ensure thread-safe access to scanner operations, particularly important when transaction rollback might occur from an expiration handler in a separate thread.

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[gemini-code-assist]

Code Review

This pull request is a backport that introduces a configuration option to enable or disable active transaction management. The changes include a significant refactoring to improve modularity and code clarity. Key improvements are:

• A new configuration property scalar.db.active_transaction_management.enabled is added.
• The logic for managing active transactions is extracted into a new generic ActiveTransactionRegistry class.
• A new AbstractDistributedTransactionProvider base class is introduced to centralize the logic for wrapping transaction managers, simplifying provider implementations.
• The Scanner interface is now wrapped with a SynchronizedScanner to ensure thread safety during transaction expiration.
• The API for handling transaction expiration has been simplified by removing the ability to set an expiration handler at runtime.

The overall changes are well-implemented and improve the design of the active transaction management feature. I have a couple of minor suggestions to improve encapsulation for some test-oriented constructors.