Muon DQMOffline fix thread un safe

Removed some unused class (MuonAnalyzerBase) , migrated to support multithread DTsegmentTask and remove thread_unsafe for the EfficiencyAnalyzer (I think is was tagged unsafe by mistake)
@folguera this has to remain a thread_unsafe module (thanks @Dr15Jones).
could you please make the change? for the rest the PR looks ok to me.
thanks,
F.