device: use subnet when the applied connection has IPv6 method shared
Summary
policy: remove the subnet for deactivating downlink device
Purpose
We should use the IPv6 subnet when we have an applied connection
stored on the downlink device, and the IPv6 method should be "shared"
for that applied connection. It does not make sense to register l3cd
and set router config for ndisc instance when the downlink device is
already deactivated.
Resolves: https://issues.redhat.com/browse/RHEL-17350
Checklist
Please read https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/blob/main/CONTRIBUTING.md before opening the merge request. In particular, check that:
-
the subject for all commits is concise and explicative -
the message for all commits explains the reason for the change -
the source is properly formatted -
any relevant documentation is up to date -
you have added unit tests if applicable