HPCC-10696 Roxie should limit size of workunit outputs

Both a default limit (10Mb) and an overridable one via MAXSIZE attribute.

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
HPCC-10696 Roxie should limit size of workunit outputs

Fix cosmetic issue in error message, spotted when testing.

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>