Don't use invalid defaults for loadouts (#28740)

* Don't use invalid defaults for loadouts

At the time it made more sense but now with species specific stuff it's better to have nothing.

* Loadout SetDefault only applies valid loadouts

Content.Client/Lobby/UI/HumanoidProfileEditor.xaml.cs

@@ -946,7 +946,7 @@ namespace Content.Client.Lobby.UI
                             if (loadout == null)
                             {
                                 loadout = new RoleLoadout(roleLoadoutProto.ID);
-                                loadout.SetDefault(_prototypeManager);
+                                loadout.SetDefault(Profile, _playerManager.LocalSession, _prototypeManager);
                             }
 
                             OpenLoadout(job, loadout, roleLoadoutProto);