Revert "Fix type error in _customization_sso"

This reverts commit 40b2df1.

I think that patch was merged to fix a bug in manual_files, but broke
root_ssh. [2] is an alternative, which should make both work.

[2] oVirt/ovirt-engine#645

packaging/setup/plugins/ovirt-engine-setup/ovirt-engine-grafana-dwh/core/config.py

@@ -220,7 +220,7 @@ def _customization_sso(self):
                 prompt=True,
                 default=True,
             )
-            with open(tmpconf, 'w') as f:
+            with open(tmpconf, 'wb') as f:
                 f.write(res)
             self._process_sso_client_registration_result(tmpconf)