Added var env loading for backend type in Qsim unit test.

Author: smaugdela

tests/test_qsim_simple_circuit.py

@@ -25,7 +25,7 @@ def test_qsim_simple_circuit():
  url=os.getenv("QISKIT_SCALEWAY_API_URL"),
  )
 
- backend = provider.get_backend("qsim_simulation_pop_c16m128")
+ backend = provider.get_backend(os.getenv("QSIM_SCALEWAY_BACKEND_NAME", "qsim_simulation_pop_c16m128"))
 
  assert backend is not None