Remove any mention of L0 in TisTos

Removed any mention of L0 in TisTos. In particular:

• Removal of all src/L0*.{cpp,h}
• Removal of all code only run if L0 is present
• The size of enum TriggerStages { defaultTriggerStage = 0, HLT1 = defaultTriggerStage, HLT2, NTriggerStages } has changed

Related MR: Analysis!643 (merged) (TupleToolTISTOS) DaVinci!408 (merged) (DaVinci configuration)

With these changes I am able to run TupleToolTISTOS on upgrade simulation (./run gaudirun.py -v Phys/DaVinci/options/DaVinci-Example.py Phys/DaVinci/options/DaVinciTestData.py) and the results seem meaningful.

Questions:

• Is Phys/TisTosTobbing/src/Hlt2TriggerTisTos.cpp needed? It addresses a run 2 bug/feature described in https://its.cern.ch/jira/browse/LHCBPS-1746 : @olupton ?
• Are there any side effects I have missed?
• Are there regions of the code that cannot be accessed any longer and should also be removed?
• Anything else that should be removed? -> Need approval of @tskwarni