HPCC-10230 FILEPOSITION(FALSE) on index removes implicit payload field.

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
HPCC-10230 Fix issues highlighted in code review

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>
Merge pull request #5349 from ghalliday/issue10230

HPCC-10230 FILEPOSITION(FALSE) on index removes implicit payload field.

Reviewed-By: Jamie Noss <james.noss@lexisnexis.com>
Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>