fdo#60668: filter out fieldmark chars from Index entries:
fdo#60668: filter out fieldmark chars from Index entries:

SwTxtNode::GetExpandTxt must filter out all dummy characters used to
represent fields, footnotes, field marks, etc.

Change-Id: Ie5ae2a82da9a6618bb451efabfd38769c495cc93

JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core