Update signature introspection test for current spec, remove all but one Rakudo fudge.
Update signature introspection test for current spec, remove all but one Rakudo fudge.

dogbert17/roast,skids/roast,skids/roast,niner/roast,dogbert17/roast,b2gills/roast,cygx/roast,dankogai/roast,niner/roast,laben/roast,b2gills/roast,skids/roast,zostay/roast,zostay/roast,dankogai/roast,b2gills/roast,cygx/roast,niner/roast,laben/roast,bitrauser/roast,cygx/roast,perl6/roast,laben/roast,zostay/roast,bitrauser/roast,dankogai/roast