HPCC-11643 Remove dummy LOADXML

This is a stage1 fix. It allows for dummy LOADXMLs to be removed
and have macro paramters declared before an internal (to macro def) LOADXML
to still exist.

This alters non of ill behavours relating to %IDs% and LOADXMLs.

Signed-off-by: jamienoss <james.noss@lexisnexis.com>
Merge pull request #6170 from jamienoss/issue9892-remove-dummy-loadxml-stage1

HPCC-9892 Remove dummy LOADXML

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>