* move GROUP_CONCAT/JSON_ARRAYAGG storage to the RowGroup from
the RowAggregation*
* internal data structures (de)serialization
* get rid of a specialized classes for processing JSON_ARRAYAGG
* move the memory accounting to disk-based aggregation classes
* allow aggregation generations to be used for queries with
GROUP_CONCAT/JSON_ARRAYAGG
* Remove the thread id from the error message as it interferes with the mtr
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