Move away from Grid sw test

The transition was initiated quite a while ago, and things seems to be fine, so this is the last step: totally remove references to the old "dirac SW-TEST" storage element (that was under /eos/lhcb/grid/prod/lhcb/swtest) and use only the non grid cern-swtest (/eos/lhcb/cern-swtest).

I made sure that all the files exist on the new destination. I would expect this MR to be totally transparent, though I have no idea how to test it :-)

One word of caution though: I have seen plenty of URLs that are referring to other sites (gridka, in2p3, etc) and even user files (!!!!!). There is absolutely no guarantee whatsoever that these files stay where they are, since they follow grid data management patterns. And if one day, such a file goes missing, "PRConfig is using it" will not be a good reason to put it back :-) So I link again the documentation, just in case :-) https://twiki.cern.ch/twiki/bin/view/LHCb/TestFileDB#Adding_files_to_CERN_SWTEST_EOS