Keep test order due to rename_privateuse1_backend is disposable (#120464)
With the change in https://github.com/pytorch/pytorch/pull/120399.
As rename_privateuse1_backend is disposable, run test_external_module_register with an renamed backend may cause problem. Try to change the testcase name and keep the right order (ASCII).
Pull Request resolved: https://github.com/pytorch/pytorch/pull/120464
Approved by: https://github.com/albanD
