When CNI ADD never completes, multus DEL fails because delegate plugins
require runtime state that only exists after a successful ADD. This
creates a deadlock where containerd cannot release sandbox name
reservations, permanently blocking pod creation on the affected node.

Build a custom multus-cni image with a patch that returns success on
DEL when no cache file exists (ADD was never completed).

Upstream PR: k8snetworkplumbingwg/multus-cni#1498
Tracking issue: #2310

Co-Authored-By: Claude <noreply@anthropic.com>
Signed-off-by: Andrei Kvapil <kvapss@gmail.com>
(cherry picked from commit 094b80a)

Co-Authored-By: Claude <noreply@anthropic.com>
Signed-off-by: Andrei Kvapil <kvapss@gmail.com>
(cherry picked from commit 1cd5643)