[CAMEL-20139]: fix for incorrect correlation key in first aggregated message

[dinurp]

Description

fix for
[CAMEL-20139]: aggregate EIP: wrong correlation key set for the first aggregate exchange

When completing aggregation, original message of the completing message was passed as original messages for all batches. Now the completing message is passed as the original message only for its batch; for others, the aggregate message in the repository is passed as the original message.

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[oscerd]

Just minor findings.