Remove redundant collectgarbage() calls from scripts

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

share/scripts/_remember_file.lua

@@ -30,8 +30,5 @@ function factory ()
 			-- unset most recently used filename on dialog "cancel"
 			file_name_testscript_last_filename = nil
 		end
-
-		od = nil
-		collectgarbage ()
 	end
 end