The clientside allowPersonalMessages function introduced
in e62e93f83a sometimes did not
work correctly, because the currentUser.groups property
only contained **visible** groups for the current user, which
could exclude auto groups that had their permissions set to
be owner-only visible.
It was unnecessary to add this anyway since we already have
can_send_private_messages on the CurrentUserSerializer. It's
better the backend does this calculation anyway. Use that
in the clientside code instead and get rid of allowPersonalMessages
d379edec8d