[RF] Remove unused `RooVectorDataStore::_weights` data member
[RF] Remove unused `RooVectorDataStore::_weights` data member

olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root