Open global config from template gui at correct location

When opening template repo settings, open at those template
repo settings, and not at the "General" page.

fixes QubesOS/qubes-issues#9530
requires QubesOS/qubes-desktop-linux-manager#227

qubesmanager/qvm_template_gui.py

@@ -704,7 +704,8 @@ def open_global_config(self, *_args):
         """
         Run global config in foreground (blocking)
         """
-        subprocess.call('qubes-global-config')
+        subprocess.call(
+            ['qubes-global-config', '-o', 'updates#template_repositories'])
         self.refresh()
 
     def _get_selected_item(self) -> typing.Optional[TreeItem]: