feat: record the migration events in metasrv

[zyy17]

I hereby agree to the terms of the GreptimeDB CLA.

Refer to a related PR or issue link (optional)

What's changed and what's your intention?

1. Add the event recorder in common/procedure with ProcedureEvent;
2. Implement the event recorder in metasrv and collect the region migration events;

PR Checklist

Please convert it to a draft if some of the following conditions are not met.

• I have written the necessary rustdoc comments.
• I have added the necessary unit tests and integration tests.
• This PR requires documentation updates.
• API changes are backward compatible.
• Schema or data changes are backward compatible.

[Copilot]

Pull Request Overview

This PR implements event recording functionality for region migration procedures in the metasrv component. The feature tracks important events during the migration lifecycle and persists them to a system table for observability and debugging purposes.

• Adds event recording infrastructure to capture region migration state changes
• Integrates event recording into the procedure manager to track migration lifecycle events
• Adds test verification to ensure migration events are properly recorded in the system table

Reviewed Changes

Copilot reviewed 30 out of 31 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
tests-integration/tests/region_migration.rs	Adds comprehensive test verification for region migration events system table
tests-integration/src/cluster.rs	Modifies cluster builder to support optional frontend server startup for test environments
src/meta-srv/src/metasrv/builder.rs	Integrates event recorder into metasrv builder and procedure manager initialization
src/meta-srv/src/events/region_migration_event.rs	Implements region migration event structure and serialization logic
src/common/procedure/src/local.rs	Adds event recording capability to procedure execution lifecycle
src/common/event-recorder/src/recorder.rs	Makes json_payload method optional with default empty implementation

Comments suppressed due to low confidence (4)

tests-integration/tests/region_migration.rs:316

• Using DEFAULT_FLUSH_INTERVAL_SECONDS * 2 directly as a Duration is incorrect. DEFAULT_FLUSH_INTERVAL_SECONDS appears to be a numeric value, but tokio::time::sleep expects a Duration. This should be Duration::from_secs(DEFAULT_FLUSH_INTERVAL_SECONDS * 2).

    run_sql(

tests-integration/tests/region_migration.rs:342

• [nitpick] The variable name procedure_id_for_closure is unnecessarily verbose and unclear. Consider renaming it to something more concise like procedure_id_clone or simply move the clone operation inline where it's used.

    let procedure_id_for_closure = procedure_id.clone();

tests-integration/tests/region_migration.rs:483

• [nitpick] The variable name procedure_id_for_closure is unnecessarily verbose and unclear. Consider renaming it to something more concise like procedure_id_clone or simply move the clone operation inline where it's used.

    let procedure_id_for_closure = procedure_id.clone();

src/meta-srv/src/events/region_migration_event.rs:82

• [nitpick] The variant name Done is ambiguous compared to other variants like Running and Failed. Consider renaming to Finished or Completed for better clarity and consistency with the comment.

    Done,

[fengjiachun]

Rest LGTM

[WenyXu]

Better to use debug fmt?

[WenyXu]

The procedure generates different dump data at each step.

[WenyXu]

Can we add a method to the Procedure trait to expose recordable metadata? And we can build the Event directly in the recorder without having to convert it to another Event implementation in the handler.