- make new reference file for  stressRooStats. Bug fixed in 48148 affected generation of dtaa set, so 
results in sim model are different since the data have changed
- change test also to increase signal fraction to get higher significance


git-svn-id: http://root.cern.ch/svn/root/trunk@48149 27541ba8-7e3a-0410-8455-c3a389f83636