Show only organizations of the region in the user setting in a region

[MizukiTemma]

Describe the Bug

If an user have access to more than one region (for example A and B) and you open the setting for this user in the region A, not only the organizations of Region A but also those of Region B are shown.

Steps to Reproduce

1. Create an user with more than one region (A and B)
2. Create an organization in A and B (if there is yet none)
3. Go to Region A
4. Go to "Users" in the menu on the left side
5. Select the user
6. See organizations of Region B are listed in the drop down "Organization"

Expected Behavior

Only the organization of the current region must be shown

Actual Behavior

All organizations of all regions of the user are shown

Additional Information

What if an user has to be assinged to an organization in each region? Possible case: User "Mustermann" has access to Region A and B. Region A has an organization α and B has an organization β. Region A wants to assingn Mustermann to α and B wants to assign Mustermann to β.

Currently one user can have only one organization.

Traceback