[BE][DTensor] add DeviceMesh test to periodic testing list (#100029)
## Why
This PR adds `test_device_mesh.py` to periodic tests because it requires more GPUs (4/8) to run testing than the CI machine has.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/100029
Approved by: https://github.com/wanchaol, https://github.com/fduwjj
