libcontainerd/supervisor: platformCleanup(): use canonical socket address

Consider Address() (Config.GRPC.Addres) to be the source of truth for
the location of the containerd socket.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

libcontainerd/supervisor/remote_daemon_linux.go

@@ -55,5 +55,5 @@ func (r *remote) killDaemon() {
 }
 
 func (r *remote) platformCleanup() {
-	os.Remove(filepath.Join(r.stateDir, sockFile))
+	_ = os.Remove(r.Address())
 }