Group initiator can give itself the Admin role on Invitation UI

Problem/Motivation

Group initiator can give itself the Admin role, even this setting is unticked in group-configuration.

Steps to reproduce

When a user create a new group without admin role, their can give this role over Member-Edit ... tick the checkbox "Admin"

Proposed resolution

Prevent to permit the admin role on own groups and/or remove "EDIT" herself for non-admins of the group. Something like that.

Remaining tasks

User interface changes

API changes

Data model changes