ctdb-scripts: Avoid failing updateip when IP is not assigned

ctdb-scripts: Avoid failing updateip when IP is not assigned

There is no use failing this when it could behave more like takeip.

Use old interface of "__none__" as a hint that ctdbd doesn't think the
IP is assigned either.  In this case print a warning instead of an
error.  Take some care to avoid spurious errors in updateip.

After commit 0536d7a98b832fc00d26b09c26bf14fb63dbf5fb (which improves
IP address state checking), this will almost certainly not occur on
platforms with getifaddrs(3) (e.g. Linux).  This means it is only
likely to occur in 4.21 when net.ipv4.ip_nonlocal_bind=1.

Update test to match.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=15935

Reported-by: Bailey Allison <ballison@45drives.com>
Signed-off-by: Martin Schwenke <mschwenke@ddn.com>
Reviewed-by: Anoop C S <anoopcs@samba.org>
Autobuild-User(master): Anoop C S <anoopcs@samba.org>
Autobuild-Date(master): Fri Oct 17 06:28:30 UTC 2025 on atb-devel-224

(cherry picked from commit 0e73781bf84a1e8e596d8be3f55eeb5f8f927990)

Autobuild-User(v4-21-test): Jule Anger <janger@samba.org>
Autobuild-Date(v4-21-test): Wed Oct 22 11:16:15 UTC 2025 on atb-devel-224