Explore if Group Deletion can be performed without a (current) user.

The Manage team is working on a feature that helps admins performed delayed deletion for groups - #33257 (closed).

However, if this action is delayed, it is possible that the user who marked a group for deletion itself is deleted from the system before the group deletion actually takes place and hence, at the time of group deletion we will not have a user to perform this action, as GroupDestroyWorker and associated services require a user to perform these actions (for permission check, audit logging etc).

So we should explore whether group deletion can be performed as a system event, ie, even without the presence of a user.

We currently follow a similar approach while deleting members with expired access from a group/project - it works even without a user. Refer: RemoveExpiredMembersWorker

Discussion: !19679 (comment 240823396)