Use a non-symmetric tetrahedron for user_mesh_test.
Use a non-symmetric tetrahedron for user_mesh_test.

PiperOrigin-RevId: 486658331
Change-Id: I96edd3b2aba916f9215661a7ba94271696690807

deepmind/mujoco,deepmind/mujoco,deepmind/mujoco,deepmind/mujoco,deepmind/mujoco