Kubernetes CNI chained plugin configuration ignored on v0.4.x

Installing a chained CNI plugin seems to be ignored on v0.4.x. The CNI config gets set properly in `/var/lib/rancher/k3s/agent/etc/cni/net.d/` and the plugin executable gets installed properly in `/var/lib/rancher/k3s/data/current/bin/`, but it's never called. No CNI-related logs are emitted, and Pods come up only with the default flannel configuration.

The CNI in question works like multus; it delegates to the default plugin (flannel) first and does other things later in the chain without interfering with it.

This works in v0.3.x. Using docker driver in both cases.

I'm going to guess that this has something to do with the addition of embedded networking with v0.4.0. I'm open to workarounds; colima is a smoother experience in my environment that minikube, but I do a lot of CNI-related things so it would be nice to have it working again.