This cleans up a log message that looks like:
I0312 14:36:50.280018 12866 operation_generator.go:869] UnmountDevice succeeded for volume "my-volume" %!(EXTRA string=UnmountDevice succeeded for volume "my-volume" (UniqueName: "kubernetes.io/csi/smb.csi.k8s.io^my-volume") on node "my-node")