Only Village-Born Iron Golems Have Vines

Only Iron Golems Generated in Villages or by Villagers should have vines. Player-Made Iron Golems make less sense to show visible aging than Villager generated Golems, so the difference between the two would make sense. This also provides an indicator of whether or not an Iron Golem is neutral or passive.

If players would like their constructed golems to have vines, they could simply right-click on the golem with vines (and remove them with shears), though this would undermine the purpose of the visual indicator.