policy-node: don't try to link to the same link-group

Avoids linking streams to a node of the same link-group because that
would be a circular link.
6 jobs for link-group-policy-fix in 2 minutes and 6 seconds (queued for 7 seconds)
Status Name Job ID Coverage
  Container
passed container_fedora #13660650

00:00:29

passed container_ubuntu #13660651

00:00:31

 
  Build
passed build_on_fedora_no_docs #13660653

00:00:45

passed build_on_fedora_with_docs #13660652

00:01:33

passed build_on_ubuntu_no_gir #13660655

00:00:43

passed build_on_ubuntu_with_gir #13660654

00:01:24