Zombies in Iron Farm?

On Minecraft server 1.14.3, is it better to hide zombies in iron farm, during the night so that villagers can sleep and produce more iron golems? Or would it be better to just leave the zombies to be seen and running around all the time?

I’m using my iron golem farm for afking and my minecraft servers are without any mods. Of course I’m always close enough so the chunks are actually loaded.