Mesh check in `make_same_mesh_connection` too strict?

@anderson2981 and @tulioricci have both run into errors in `make_same_mesh_connection` when restarting with different orders. Specifically, this check is failing:

```python
if from_discr.mesh is not to_discr.mesh:
raise ValueError("from_discr and to_discr must be based on "
"the same mesh")
```
I suspect it's related to the mesh boundary tag relabeling that grudge does when constructing `DiscretizationCollection`s. Strangely, though, changing the check condition to

```python
if from_discr.mesh.groups is not to_discr.mesh.groups:
...
```
doesn't appear to help, so maybe something else is going on? (_Edit:_ I don't think this would be correct anyway, since it wouldn't detect transformed meshes.)

This can be worked around for now by just commenting out the check, but I should take a closer look.