HLT validation improvements

In order to avoid overloading confdb when many hltval jobs all run hltGetConfiguration at the same time querying and customisation of the HLT menu for the validation is now done during during submit() and the HLT menu is stored for later use in a resubmission. This way hltGetConfiguration run only once per submitted fill. In addition, the wildcard to select HLTPhysics datasets has been removed since in some cases up to 10k validation jobs were created when HLTPhysics0-20 datasets existed as well. Finally, since the root files usually only contain around 5k events jobs are now created for three input files instead of one.