[MC-248272] Enchantment::doPostHurt and Enchantment::doPostAttack are called twice for players

The Enchantment::doPostHurt and Enchantment::doPostAttack functions are called twice for the player causing some bugs.

The Bane of Arthropods enchantment gives the Slowness effect twice
The Thorns enchantment deals damage to the attacker and the durability of the item with this enchantment twice.

The problem is that the EnchantmentHelper::doPostHurtEffects and EnchantmentHelper::doPostDamageEffects actually call these functions twice:

Vanilla code 1.18.1-1.20.1

public static void doPostHurtEffects(LivingEntity defender, Entity attacker) {
    EnchantmentVisitor consumer = (enchantment, lvl) -> enchantment.doPostHurt(defender, attacker, lvl);

    if (defender != null) {
        EnchantmentHelper.runIterationOnInventory(consumer, defender.getAllSlots());
    }
    if (attacker instanceof Player) {
        EnchantmentHelper.runIterationOnItem(consumer, defender.getMainHandItem());
    }
}

public static void doPostDamageEffects(LivingEntity attacker, Entity target) {
    EnchantmentVisitor consumer = (enchantment, lvl) -> enchantment.doPostAttack(attacker, target, lvl);

    if (attacker != null) {
        EnchantmentHelper.runIterationOnInventory(consumer, attacker.getAllSlots());
    }
    if (attacker instanceof Player) {
        EnchantmentHelper.runIterationOnItem(consumer, attacker.getMainHandItem());
    }
}

Fix suggestion

public static void doPostHurtEffects(LivingEntity defender, Entity attacker) {
    EnchantmentVisitor consumer = (enchantment, lvl) -> enchantment.doPostHurt(defender, attacker, lvl);

    if (defender != null) {
        EnchantmentHelper.runIterationOnInventory(consumer, defender.getAllSlots());
    } else if (attacker instanceof Player) {
        EnchantmentHelper.runIterationOnItem(consumer, defender.getMainHandItem());
    }
}

public static void doPostDamageEffects(LivingEntity attacker, Entity target) {
    EnchantmentVisitor consumer = (enchantment, lvl) -> enchantment.doPostAttack(attacker, target, lvl);

    if (attacker != null) {
        EnchantmentHelper.runIterationOnInventory(consumer, attacker.getAllSlots());
    } else if (attacker instanceof Player) {
        EnchantmentHelper.runIterationOnItem(consumer, attacker.getMainHandItem());
    }
}