Earlier we use to restrict admins, moderators or members of a group to
manage that group if they were part of the realm wide
`can_manage_all_groups`. We will not do that anymore and even
non-members of a group regardless of role can manage a group if they are
part of `can_manage_all_groups`.
See
https://chat.zulip.org/#narrow/stream/101-design/topic/Group.20add.20members.20dropdown/near/1952902
to check more about the migration plan for which this is the last step.
Tim Abbott
Shubham Padia