Delete old code that's not necessary

[taoeffect]

Problem

There's some code we don't need after we wipe everything.

E.g. from #2514:

  // For compatibility for old contracts.
  // TODO: This is to be deleted in a later release, once contracts are recreated.
  'state/vuex/commit': (key, data) => {
    switch (key) {
      case 'deleteChatRoomScrollPosition':
      case 'setChatRoomScrollPosition':
        return sbp('okTurtles.events/emit', NEW_CHATROOM_UNREAD_POSITION, data)
      // These are handled by events
      case 'removeNotification':
        return
      case 'setCurrentChatRoomId':
        return
    }

    throw new Error('Invalid selector `state/vuex/commit`: Not allowed in SW.')
  }

There might be some other code in the project we won't need anymore for the "Final breaking changes" milestone.

Solution

Remove this code. For some of the old code, e.g. upgrade code, it would be better to comment it out instead of removing it, as it will remain as a useful example for when we need to perform upgrades again.