user groups: Fix right panel display for new user group on small screen.

Opening create user group from `+` button on left panel did not
open the create user group form properly on small viewports.

This was due to show_right_section not being called which is
resposible to handle this.

web/src/user_groups_settings_ui.js

@@ -71,6 +71,9 @@ export const show_user_group_settings_pane = {
 };
 
 export function do_open_create_user_group() {
+    // Only call this directly for hash changes.
+    // Prefer open_create_user_group().
+    show_right_section();
     user_group_create.create_user_group_clicked();
 }