Fix T83725 Inconsistent vertex group between exact and fast boolean.

This makes the exact boolean have zero weights for any vertex groups
on any newly created vertices, which is what the fast solver does.

The exact boolean solver was interpolating vertex data when interpolating
loop data in newly created faces. Not sure why I chose that. The Fast
boolean solver doesn't do that, so I stopped doing it too.

source/blender/bmesh/tools/bmesh_boolean.cc

@@ -296,7 +296,7 @@ static bool apply_mesh_output_to_bmesh(BMesh *bm, IMesh &m_out, bool keep_hidden
         BMIter liter;
         BMLoop *l = static_cast<BMLoop *>(BM_iter_new(&liter, bm, BM_LOOPS_OF_FACE, bmf));
         while (l != nullptr) {
-          BM_loop_interp_from_face(bm, l, orig_face, true, true);
+          BM_loop_interp_from_face(bm, l, orig_face, false, true);
           l = static_cast<BMLoop *>(BM_iter_step(&liter));
         }
       }