Clean up UI for pytest machine config (#204)

- when exiting due to assertion, make the message more focused by
  avoiding pytests INTERNALERROR wrapper and whole stacktrace
- also add suggestion of available --ignore_machine_config override

conftest.py

@@ -26,8 +26,11 @@ def set_fuser(fuser):
  torch._C._jit_set_texpr_fuser_enabled(True)
 
 def pytest_sessionstart(session):
- if not session.config.getoption('ignore_machine_config'):
+ try:
  check_machine_configured()
+ except Exception as e:
+ if not session.config.getoption('ignore_machine_config'):
+ pytest.exit(f"{e}\nUse --ignore_machine_config arg if not running with recommended tuning settings")
 
 def pytest_configure(config):
  set_fuser(config.getoption("fuser"))