Change presenter get_user_related_models

[Elblinator]

Current behaviour:
The presenter currently gives back meeting ids even if the User is only in there as a remnant and not as a informational important User:
Example response if the User is not ANYMORE in the meeting (but was in there before) and has no other connections to the meeting:

id: 5
is_active_in_organization_id: 1
name: "Meetings Name ABC"

Example response from the presenter if the User is a candidate, a submitter, a speaker and a manager in the same meeting:

{
  "id": 6,
  "name": "Meeting name",
  "is_active_in_organization_id": 1,
  "speaker_ids": [ 20 ],
  "motion_submitter_ids": [ 40 ],
  "assignment_candidate_ids": [ 7 ]
}

Reproduction to get the first response:
It is important that you add User C to (at least) two meetings before removing/deleting them from any

1. Create User C
2. Create two meetings
3. Add C to both meetings
4. In Meeting A delete User C
5. In meeting B delete User C
6. Navigate to the account list
7. C has no assigned Meetings
8. Delete User C from the account list
9. In the deletion dialog both meetings will be listed

Wanted behaviour:
If a User only has a meeting_user_id but is not assigned to any group, or is in one of the other groups (candidate, submitter, speaker) then this meeting Id should not be returned by the presenter

[MSoeb]

Issue is reopened again, because the fix doesn't work well. The old meetings of the user, in which he isn't participant anymore, are still visible.

[luisa-beerboom]

And what did you do to get that result?

[MSoeb]

The reproduction steps that are listed above.