Fix PhysVal BTag config

Follow up to !65311 (merged)

Fixes the argument name to match https://gitlab.cern.ch/atlas/athena/-/blob/main/PhysicsAnalysis/JetTagging/JetTagValidation/JetTagDQA/src/PhysValBTag.cxx#L71

    declareProperty( "GN2v00TaggerName", m_GN2v00Name = "GN2v00");

FYI @ywng