KIP-1074 — Allow the replication of user internal topics

Accepted Kafka 4.0 MirrorMaker

Adds a `replication.policy.internal.topic.separator.enabled` configuration (and related `ReplicationPolicy` changes) so MirrorMaker2 can replicate user-defined topics whose names end in `.internal` or `-internal`. The current `ReplicationPolicy.isInternalTopic()` logic unconditionally excludes any topic matching the internal naming pattern, silently dropping replication of legitimate business topics with those suffixes.

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