HPCC-11020 Leaking rows in the streamed embed plugins

Make sure rows are released after use.

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
Merge pull request #5529 from richardkchapman/embed-stream-leak

HPCC-11020 Leaking rows in the streamed embed plugins

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>