[hyprland] Run eww only once.

system/hosts/vega/drew.nix

@@ -32,7 +32,7 @@
   wayland.windowManager.hyprland.settings = {
     # Set up eww here because it's based on the monitor configuration
     # Eww is idempotent, so it's fine to just run it on every reload to make sure things are open
-    exec = [
+    exec-once = [
       "sleep 2 && eww open-many vertical-statusbar"
     ];
     # Set up workspaces for this system