Remove references to savedFieldMapping in page 2 of the import

Remove references to savedFieldMapping in page 2 of the import

I do not believe this is ever assigned and I also don't think it makes sense
if assigned - the first page 'DataSource.tpl' is the one that displays the
option to load a field mapping. This code applies to the second page and
conditionally displays help text which seems to have stopped being true long ago