Make all open Working Groups known to the repo manager by default

[dontcallmedom]

At the moment, each group (working group or community group) has to be manually added as in scope of the repo manager via the admin interface.

The motivation of not adding all the groups is to keep the list of groups manageable, and since initially, the repo manager was not used by all groups, it made sense to keep that list manually updated.

Now that pretty much all working groups are expected to use it, it would probably make sense to add all open working groups to our list by default