Remove redundant collectgarbage() calls from scripts

Since 8112d6472e garbage is automatically collected
after running a Lua GUI script.

share/scripts/_vca_slave_assign.lua

@@ -65,9 +65,5 @@ function factory () return function ()
 	else
 		LuaDialog.Message ("VCA Slave Example", "Recursive VCA assignment ignored", LuaDialog.MessageType.Info, LuaDialog.ButtonType.Close):run ()
 	end
-
-	-- drop references
-	mst = nil slv = nil
-	collectgarbage ()
-end end
+:nd end