[MC-206724] Pointless restriction in count feature placement modifier

The bug

The count feature placement modifier is limited to 256. This is pointless since one can achieve much higher counts by simply repeating multiple count modifiers after each other.

Invalid placed feature

{
  "feature": "foo:bar",
  "placement": [
    {
      "type": "minecraft:count",
      "count": "400"
    }
  ]
}

Valid placed feature

{
  "feature": "foo:bar",
  "placement": [
    {
      "type": "minecraft:count",
      "count": "100"
    },
    {
      "type": "minecraft:count",
      "count": "4"
    }
  ]
}