HPCC-9892 Remove dummy LOADXML

This is a stage1 fix. It allows for dummy LOADXMLs to be removed
and have macro parameters declared before an internal (to macro def) LOADXML
to still exist.

This alters none of the ill behaviours relating to %IDs% and LOADXMLs.

Signed-off-by: jamienoss <james.noss@lexisnexis.com>
This was the least intrusive way that I could see to remove the need for a dummy load and still recreate the other silly behaviours of LOADXML and macro scoped ID's. 

A very good point about using !ret.length, I will change.