sink: encode conflict key hashes in dml events

[wk989898]

What problem does this PR solve?

Issue Number: close #4582

What is changed and how it works?

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[gemini-code-assist]

Summary of Changes

Hello, 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 significantly optimizes the conflict detection mechanism for the MySQL sink by pre-computing and encoding conflict key hashes directly within DML events. This change allows downstream components, particularly the causality detector, to reuse these hashes, reducing redundant computations and improving overall performance. It also refines the slot allocation logic within the conflict detector for better efficiency.

Highlights

• Pre-computed Conflict Hashes: DML events now pre-compute and store conflict key hashes directly for MySQL sink types, eliminating redundant calculations in the causality detector.
• Optimized Slot Mapping: The causality conflict detector's slot allocation logic has been enhanced with specialized, faster hash-to-slot mapping functions for power-of-two slot counts.
• Centralized Event Helpers: Common utility functions related to DML event processing, such as row key generation, have been moved to a shared pkg/common/event package.
• Sink Type Propagation: The SinkType is now propagated through the DispatcherService interface and DispatcherRequest protobuf, allowing downstream components to adapt behavior based on the sink type.

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[wk989898]

/test all

[gemini-code-assist]

Code Review

This pull request refactors the conflict key hash generation by moving it into the DML event encoding process, which is a good improvement for encapsulation and performance. The changes are extensive but look solid. I've found one area for a minor performance optimization.

[wk989898]

/test all

[wk989898]

/test pull-cdc-mysql-integration-light

[wk989898]

/test all

[ti-chi-bot]

@wk989898: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-error-log-review	291e073	link	true	/test pull-error-log-review

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[wk989898]

/test mysql