Halt window switcher on Reconfigure

There was an invalid memory access (since introduction of thumbnail
style in 2e9292b) with following steps:

1. Press Alt-Tab
2. Update `<windowSwitcher><osd><style>` from `classic` to `thumbnail`
3. Run `Reconfigure`
4. Press Alt-Tab again

...because `cycle_osd_thumbnail_update()` is called even though
`cycle_osd_output->items` holds `cycle_osd_classic_item`.

This commit halts window switcher on `Reconfigure` to clear
`cycle_osd_output->items` and avoid that invalid memory access.

src/server.c

@@ -97,6 +97,7 @@ reload_config_and_theme(struct server *server)
 		view_reload_ssd(view);
 	}
 
+	cycle_finish(server, /*switch_focus*/ false);
 	menu_reconfigure(server);
 	seat_reconfigure(server);
 	regions_reconfigure(server);