kube-multus serves the CNI call for every pod sandbox on its node, and
its 100m CPU limit was hardcoded in the patched upstream template.
After a CNI outage a node had ~600 dead sandboxes and 220 pods waiting:
multus was throttled in every CFS period, calls outlived kubelet's
two-minute CRI deadline, each retry grew the queue, and the node never
recovered. With the CPU limit lifted the 1Gi memory limit OOM-looped;
2 CPU and 4Gi cleared the backlog in about three minutes.

Resources now come from values, defaulting to the same requests, no
CPU limit and a 4Gi memory limit. The memory limit stays so the pod
cgroup keeps memory.max and remains outside the Talos OOM handler's
candidate set.

Since an explicit null in a values override could drop either memory
key, the render now fails without limits.memory or requests.memory.
Without the request it defaults to the limit, and a node with less
allocatable memory than that is left without multus.

Assisted-by: LLM
Signed-off-by: Aleksei Sviridkin <[email protected]>
(cherry picked from commit dca2e4f)