homes: mousqueton: use system jujutsu

They have a custom `jj` with Piper CitC integration.

hosts/homes/ambroisie@mousqueton/default.nix

@@ -25,6 +25,10 @@
       package = pkgs.emptyDirectory;
     };
 
+    jujutsu = {
+      package = pkgs.emptyDirectory;
+    };
+
     tmux = {
       # I use scripts that use the passthrough sequence often on this host
       enablePassthrough = true;