KIP-732 — Deprecate eos-alpha and replace eos-beta with eos-v2

Accepted Kafka 3.0 StreamsTransactions

Deprecates `processing.guarantee=eos-alpha` in Kafka Streams 3.0 (originally called `exactly_once`) and renames `eos-beta` (introduced in KIP-447) to `eos-v2`. The `eos-alpha` mode uses per-task producers with higher overhead; `eos-v2` (thread-level producer) is more efficient and scalable, and keeping both modes adds significant code complexity.

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