[vote] Discuss migration of entitled users

In the current system, we have the field [poll/entitled_users_at_stop]](https://github.com/OpenSlides/openslides-meta/blob/a110ca05c5fb3324f07df6215d00af555bc6b659/collections/poll.yml#L92-L94)

In the new system, we will have the field poll/entitled_meeting_user_ids.

Both are different, but have a the same purpose.

It is not possible to make a direct migration. The old field only has the users at stop, the new filed has all users, from start to stop.

If we make a migration, we would tell the wrong thing for old polls.

The field poll/entitled_meeting_user_ids is not required. We will not calculate it for all polls. For example, it will not be calculated for polls with delegations. So for the code, it would not be harmful, if the field is not set for old polls.

The question is, if we should create a migration or not.