FIX: Trying to fix duplication drop issue

[kiriharu]

Explanation:

Every time, when I break blocks with active multiply_drops effect I get much more drops then expected.
For example, if I have this config:

effects:
  - id: multiply_drops # Bonus Multiplier
    args:
      chance: 100 
      multiplier: 2
    triggers:
      - block_item_drop
    filters:
      player_placed: true
      blocks:
        - "iron_ore"

I expect to get 2 raw iron, but instead, I get 512 + 2.
Same issue when I use fortune argument.

I spent some time in debugger and found a solution - when EditableBlockDropEvent#items clear all modifiers after itemstack modification - all works as expected. But I don't think it's right, because I don't fully understand architecture.