ref(consumer): set message.max.bytes for DLQ/BLQ producers

[kylemumma]

the dlq isnt actually used right now, so this should be fine. the value aligns with the topic https://github.com/getsentry/sentry-kafka-schemas/blob/main/topics/snuba-items.yaml#L18

Summary

• Override `message.max.bytes` to 10MB on the DLQ producer `KafkaConfig` in `consumer.rs`. This config is also cloned for the BLQ producer, so both get the same broker-max limit.
• Mirrors the existing override already applied to the Python replacements producer in `snuba/consumers/consumer_builder.py`.

Test plan

• `cargo check -p rust_snuba` passes locally
• Consumer starts cleanly and produces to DLQ/BLQ topics with large payloads that previously would have exceeded the 1MB default

🤖 Generated with Claude Code

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