Locked Out Participant: error with deletion. users can't be orga/superadmins

[MSoeb]

Describe the bug
If a locked user is deleted from a meeting, the locked out state still exists in the background. This leads to the undesired behavior, that the user can't be granted with additional admin rights like orgaadmin or superadmin.

How to Reproduce

1. create a meeting A and meeting B.
2. open the meeting A
3. create a user in the meeting A. Add it also in meeting B.
4. open meeting A. Lock the user out from the meeting and delete it.
5. open account menu > user details > change user permission to orgaadmin or superadmin. Not possible, because locked out state still exists.

Expected behavior
If a user is locked out and than deleted from a meeting, it should still be possible to grant the user superadmin or orgaadmin rights.

The action should overwrite the locked out state.

[luisa-beerboom]

Based on the description I am 99% sure this'll go away once #3206 is merged.

Explanation:
We currently don't "delete" users from meetings, we just remove their groups.
The code interprets that as being gone from the meeting, but in the background the data is still there. Along, at times, with the related functionality.
In issue #2111 we decided we would change that to actually deleting the meeting user data from now on, because exactly this kind of thing will happen if this quirk in our functionality is not noted in the development of new features, and #3206 just so happens to be the PR for that issue.

[luisa-beerboom]

Added a test to the PR, it works.
We can consider this solved once #3206 is merged.