Sparse ten_J and ten_J_colind

PiperOrigin-RevId: 869712136
Change-Id: Id2979684aa0c39552cb8453852483cbac55f0ea3

python/mujoco/structs_wrappers.cc

@@ -747,7 +747,6 @@ void MjDataWrapper::Serialize(std::ostream& output) const {
 
   // Write buffer and arena contents
   {
-    MJDATA_POINTERS_PREAMBLE((this->model_->get()))
 
 #define X(type, name, nr, nc)    \
   WriteBytes(output, ptr_->name, \
@@ -827,7 +826,6 @@ MjDataWrapper MjDataWrapper::Deserialize(std::istream& input) {
 
   // Read buffer and arena contents
   {
-    MJDATA_POINTERS_PREAMBLE((&m))
 
 #define X(type, name, nr, nc) \
   ReadBytes(input, d->name, sizeof(type) * (m.nr) * (nc));