Improve Kafka event publishing reliability

[maliming]

Resolves #24340

[Copilot]

Pull request overview

This PR enhances Kafka event publishing reliability by implementing stronger guarantees for message delivery and adding validation to detect failures. The changes focus on ensuring that published events are actually persisted to Kafka before considering the operation successful.

Key Changes:

• Configured Kafka producers with Acks.All and EnableIdempotence=true to prevent message loss and duplicates
• Added PersistenceStatus validation after publishing events, throwing exceptions on failure instead of silently continuing
• Changed from fire-and-forget Produce() to awaited ProduceAsync() for proper async/await patterns and error detection

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 5 comments.

File	Description
ProducerPool.cs	Sets default Kafka producer reliability configurations (Acks.All, EnableIdempotence=true) and removes trailing whitespace
KafkaDistributedEventBus.cs	Fixes async modifier ordering, validates persistence status after publishing, and changes from synchronous Produce() to asynchronous ProduceAsync() with proper awaiting

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