Zombies should seek out zombie horses to ride them

I believe this could be the unique bond between zombies and zombie horses.

If a zombie spots a zombie horse and the zombie is pretty close to it, then it should hop on the zombie horse and pilot it around and try to go head on to the player.

If a zombie gets bored while riding a zombie horse since theres no players/action going on than it can just hop off if it feels like it.