CSI Spec v1.5.0 introduced a new Capability SINGLE_NODE_MULTI_WRITER, which specializes the SINGLE_NODE_WRITER volume access mode into the "sub"-access modes SINGLE_NODE_SINGLE_WRITER and SINGLE_NODE_MULTI_WRITER.

This was added because the existing spec was conflicting. We currently behave like SINGLE_NODE_MULTI_WRITER, so we should just use that in the code.

This requires upgrading all our sidecar containers.

We can also enable the Kubernetes E2E tests flag Feature:SELinuxMountReadWriteOncePod once we have implemented this.